ebook 241-1

Transcription

1 C 1 C C C 1.1 hello, world C hello, world #include <stdio.h> main() printf("hello, world\n");

2 2 C U N I X. c h e l l o. cc hello.c a. o u t a. out a. o u t hello, world #include <stdio.h> main() main main printf("hello, world\n"); main printf \n C C F O RT R A N P a s c a l m a i n m a i m a i n m a i m a i n #include <stdio.h> C 7 B m a i n m a i n printf("hello, world\n"); "hello, world\n" p r i n t f p r i n t f "hello, world\n" p r i n t f C \ n \ n p r i n t f \ n \ printf("hello, world

3 1 3 "); C p r i n t f #include <stdio.h> main() printf("hello, "); printf("world"); printf("\n"); \ n \ n C \ t \ b \" \\ hello, world 1-2 p r i n t f \ c c 1.2 C = (5/9) ( F 3 2 )

4 4 C m a i n hello, world #include <stdio.h> /* fahr = 0, 20,..., 300 main() int fahr, celsius; int lower, upper, step; lower = 0; upper = 300 ; step = 20; /* /* /* fahr = lower; while (fahr <= upper) celsius = 5 * (fahr-32) / 9; printf("%d\t%d\n", fahr, celsius); fahr = fahr + step; /* fahr=0, 20,..., 300 /* * / C int fahr, celsius; int lower, upper, step; i n t f l o a i n t f l o a t i n ~ f l o a t i n t f l o a t C c h a r s h o r t

5 1 5 l o n g d o u b l e 4 lower = 0; upper = 300 ; step = 20; fahr = lower; w h i l e while (fahr <= upper)... w h i l e f a h r u p p e r f a h r u p p e r w h i l e while (i < j) i = 2 * i; w h i l e C celsius = 5 * (fahr-32) / 9; c e l s i u s / 9 C / p r i n t f p r i n t 7 %

6 6 C 2 3 % d printf("%d\t%d\n", fahr, celsius); f a h r c e l s i u s \ t p r i n t f 1 % 2 3 n p r i n t f C C p r i n t f C A N S I p r i n t f C s c a n f s c a n f p r i n t f p r i n t f 1 % d printf("%3d %6d\n", fahr, celsius); f a h r c e l s i u s f a h r 3 c e l s i u s F #include <stdio.h> /* fahr = 0, 20,..., 300 main() float fahr, celsius; int lower, upper, step; lower = 0; upper = 300 ; step = 20; /* /* /*

7 1 7 fahr = lower; while (fahr <= upper) celsius = (5.0 / 9.0) * (fahr-32.0); printf("%3.0f %6.1f\n", fahr, celsius); fahr = fahr + step; f a h r c e l s i u s f l o a t 5 / / 9. 0 fahr fahr = lower; while ( fahr <= upper ) i n t f l o a t p r i n t f % 3. 0 f f a h r 3 % 6. 1 f c e l s i u s % f % 6 f 6 %. 2 f % f % d % 6 d 6 % f % 6 f 6 %. 2 f % 6. 2 f 6 p r i n t f % o % x % c % s % %

8 8 C for # include <stdio.h> /* main( ) int fahr; for ( fahr = 0; fahr <= 300; fahr = fahr + 20 ) printf ( "%3d # %6.1f\n", fahr, (5.0 / 9.0) * (fahr - 32 ) ); f a h r i n t f o r p r i n t f 3 p r i n t f 3 % 6. 1 f f o r w h i l e w h i l fahr = 0 fahr <= 300 p r i n t f fahr = fahr + 20 w h i l e f o r w h i l e f o r f o r f o r w h i l e

9 # d e f i n e #define # d e f i n e #include <stdio.h> #define LOWER 0 /* #define UPPER 300 /* #define STEP 20 /* /* - main ( ) int fahr; for ( fahr = LOWER; fahr <= UPPER; fahr = fahr + STEP ) printf ( "%3d %6.1f\n", fahr, (5.0 / 9.0) * (fahr - 32 ) ); L O W E R U P P E R S T E P # d e f i n e C g e t c h a r p u t c h a r g e t c h a r c = getchar () c

10 10 C 7 p u t c h a r putchar ( c ) c p u t c h a r p r i n t f g e t c h a r p u t c h a r while C #include <stdio.h> /* 1 main ( ) int c; c = getchar ( ); while ( c!= EOF ) putchar ( c ); c = getchar ( );! = c h a r i n t C g e t c h a r E O F end of file c g e t c h a r c c h a r c E O F c i n t E O F < s t d i o. h > c h a r E O F C

11 1 11 c = getchar ( ) = c w h i l e #include <stdio.h> /* 2 main ( ) int c; while ( (c = getchar ( ) )!= EOF ) putchar ( c ); w h i l e c w h i l e w h i l e w h i l m a i n g e t c h a r w h i l e! = =! c = getchar ( )!= EOF c = ( getchar ( )!= EOF ) c 0 1 g e t c h a r getchar ( )!= EOF E O F #include <stdio.h> /* 1 main ( ) long nc;

12 12 C nc = 0; while ( getchar ( )!= EOF ) ++nc; printf("%ld\n", nc); ++nc; nc = nc + 1; + + n c n c n c n c n c + + n c 1 i n t l o n g l o n ( ) 32 i n t l o n g i n t i n t % l d p r i n t f l o n g d o u b l e ( ) w h i l e f o r #include <stdio.h> /* 2 main ( ) double nc; for ( nc = 0; getchar ( )!= EOF; ++nc ) ; printf("%.0f\n", nc); % f f l o a t d o u b l e %. 0 f 0 f o r C f o r f o r w h i l e f o r g e t c h a r 0 w h i l e f o r 0 w h i l e f o r

13 #include <stdio.h> /* main ( ) long c, nl; nl = 0; while ( (c = getchar ( ) )!= EOF ) if ( c =='\n' ) ++nl; printf("%d\n", nl); w h i l e i f i f + + n l i f = = C P a s c a l = F O RT R N. E Q. C = = C = = = 2 'A' A S C I I 65 A 65 ' A ' 65 ' A ' '\n' A S C I I 10 '\ n ' "\ n " \ t \ b \\ 1.5.4

14 14 C U N I X w c #include <stdio.h> #define IN 1 /* #define OUT 0 /* /* main ( ) int c, nl, nw, nc, state; state = OUT; nl = nw = nc = 0; while ( (c = getchar ( ) )!= EOF ) ++nc; if ( c =='\n' ) ++nl; if ( c == ' ' c == '\n' c == '\t' ) state = OUT; else if ( state == OUT ) state = IN; ++nw; printf("%d %d %d\n", nl, nw, nc); s t a t e O U T I N O U T 1 0 nl = nw = nc = 0; n l nw n c 0 nl = ( nw = ( nc = 0 )); O R if ( c == ' ' c == '\n' c == '\t' ) c c c \ t

15 1 15 && A N D && c e l s e i f if ( ) else 1 2 i f - e l s e 1 2 e l s e i f i f C 12 1 #include <stdio.h> /* main ( ) int c, i, nwhite, nother; int ndigit[10]; nwhite = nother = 0; for ( i =0; i < 10; ++i ) ndigit[i] = 0; while ( ( c = getchar() )!= EOF ) if ( c >= '0' && c <= '9' ) ++ndigit[c - '0']; else if ( c == ' ' c == '\n' c == '\t' ) ++nwhite; else

16 16 C ++nother; printf( "digits =" ); for ( i =0; i < 10; ++i ) printf( " %d", ndigit[i] ); printf( ", white space = %d, other = %d/n", nwhite, nother); digits = , white space = 123, other = 345 int ndigit[10]; n d i g i t 10 C 0 10 n d i g i t [ 0 ] n d i g i t [ 1 ] n d i g i t [ 9 ] f o r i if ( c >= '0' && c <= '9' )... c c - '0' ' 0 ' ' 1 ' ' 9 ' c h a r c h a r i n t c - '0' c ' 0 ' ' 9 ' 0 9 n d i g i t if ( c >= '0' && c <= '9' ) ++ndigit[c - '0']; else if ( c == ' ' c == '\n' c == '\t' ) ++nwhite; else ++nother; if ( ) 1 1 else if ( ) 2 2 else n

17 1 17 i f e l s e e l s e i f i f e l s e 0 else if ( ) i f e l s e 3 s w i t c h 3. 4 s w i t c h C F O RT R A N P a s c a l C p r i n t f g e t c h a r p u t c h a r C F O RT R A N ** power(m, n) power(m, n) m n p o w e r ( 2, 5 ) 32 x y pow(x, y) power(m, n) #include <stdio.h> int power(int m, int n); /* power main ( ) int i; for ( i =0; i < 10; ++i )

18 18 C printf("%d %d %d\n", i, power(2, i), power(-3, i)); return 0; /* power: n n >=0 int power(int base, int n) int i, p; p = 1; for ( i = 1; i <= n; ++i ) p = p * base; return p; C m a i n p o w e r printf("%d %d %d\n", i, power(2, i), power(-3, i)); p o w e r p o w e r power(2, i) i 4 p o w e r int power(int base, int n) p o w e r p o w e r i p p o w e r i m a i n i p o w e r r e t u r n m a i n r e t u r n return r e t u r n

19 1 19 m a i n r e t u r n m a i n 0 0 m a i n r e t u r n m a i n r e t u r n m a i n int power(int m, int n); p o w e r i n t i n t p o w e r int power(int, int); ANSI C C C p o w e r /* power: n n >=0 /* power(base, n) int base, n; int i, p; p = 1; for ( i = 1; i <= n; ++i ) p = p * base; return p; i n t ANSI C p o w e r int power( ); p o w e r p o w e r i n t ANSI C

20 20 C F O RT R A N C C F O RT R A N P a s c a l v a r C p o w e r /* power: n n >=0 2 int power(int base, int n) int p; for ( n = 1; n > 0; --n ) p = p * base; return p; n f o r 0 i p o w e r n p o w e r C while ( ) if ( )

21 1 21 g e t l i n e g e t l i n e c o p y m a i n g e t l i n e c o p y #include <stdio.h> #define MAXLINE 1000 /* int getline (char line[ ], int maxline ); void copy ( char to[ ], char from [] ); /* main ( ) int len; /* int max; /* char line[maxline]; /* char longest[maxline]; /* max = 0; while ( ( len = getline (line, MAXLINE) ) > 0 ) if (len > max) max = len; copy ( longest, line ); if (max > 0) /* printf ("%s", longest ) ; return 0 ; /* getline s int getline (char s [ ], int lim) int c, i; for (i = 0; i < lim -1 && (c = getchar ( ) )!= EOF && c!= '\n'; ++i ) s[i] = c;

22 22 C if (c == '\n' ) s[i] = c; ++i; s[i] = '\0'; return i; /* copy from to; to void copy ( char to [ ], char from [ ]) int i; i = 0; while ( ( to[ i ] = from [ i ])!= '\0') ++i; g e t l i n e c o p y m a i n g e t l i n e g e t l i n int getline (char s [ ], int lim) s l i m g e t l i n e s m a i n p o w e r g e t l i n e r e t u r n g e t l i n e i n t i n t c o p y c o p y v o i d g e t l i n e '\ 0 ' 0 C C "hello\n" '\0' h e l l o \n \0 p r i n t f % s c o p y '\0' '\0' m a i n g e t l i n e m a i n

23 1 23 g e t l i n e g e t l i n c o p y 1-16 m a i n reverse ( s ) s 1.10 m a i n l i n e l o n g e s t m a i n m a i m a i n g e t l i n e i c o p y i 4 F O RT R A N C O M M O N P a s c a l e x t e r n l i n e l o n g e s t m a x #include <stdio.h> #define MAXLINE 1000 /* int max; /* char line[maxline]; /*

24 24 C char longest[maxline]; /* int getline (void ); void copy ( void ); /* main ( ) int len; extern int max; extern char longest[ ]; max = 0; while ( ( len = getline ( ) ) > 0 ) if (len > max) max = len; copy ( ); if (max > 0) /* printf ("%s", longest ) ; return 0 ; /* getline int getline (void ) int c, i; extern char line[ ]; for (i = 0; i < MAXLINE -1 && (c = getchar ( ) )!= EOF && c!= '\n'; ++i ) line[i] = c; if (c == '\n' ) line[i] = c; ++i; line[i] = '\0'; return i; /* copy void copy ( void ) int i; extern char line[ ], longest[ ]; i = 0; while ( ( longest[ i ] = line [ i ])!= '\0')

25 i; m a i n g e t l i n e c o p y e x t e r n e x t e r n e x t e r n e x t e r n m a i n g e t l i n e c o p y e x t e r n e x t e r n f i l e 1 f i l e 2 f i l e 3 f i l e 2 f i l e 3 e x t e r n e x t e r # i n c l u d e.h < s t d i o. h > 4 7 B g e t l i n e c o p y getline( ) copy( ) C C v o i d C 1-20 d e t a b n 1-21 e n t a b

26 26 C d e t a b 1-22 n 1-23 C C 1-24 C

27 C 2 ANSI C s i g n e d u n s i g n e d long double c o n s t x X ANSI C 6 i f e l s e i n t f l o a t 2.2 C

28 28 C c h a r i n t f l o a t d o u b l e s h o r t l o n g short int sh; long int counter; i n t s h o r t l o n g i n t s h o r 16 l o n g 32 s h o r t i n t 16 l o n g 32 s h o r t i n i n t l o n g s i g n e d u n s i g n e d c h a r u n s i g n e d 0 2 n n c h a r 8 unsigned char 0 ~ 255 signed char 128 ~ 127 c h a r long double float double long double < l i m i t s. h > < f l o a t. h > B 2-1 s i g n e d u n s i g n e d c h a r s h o r t i n t l o n g i n t l o n g l L L i n t l o n g u U u l U L unsigned long e 2 d o u b l e f F f l o a t l L long double 0 0 x 0 X x 1 f 0 X 1 F l L l o n g u U u n s i g n e d 0 X F U L unsigned long 15

29 2 29 ' x ' A S C I I '0' 48 0 '0' 48 \ n '\ooo' o o o 1 ~ '\xhh' h h 0 9 a f A F #define VTAB '\013' #define BELL '\007' #define VTAB '\xb' #define BELL '\x7' /* ASCII /* ASCII /* ASCII /* ASCII \a \\ \b \? \f \' \n \" \r \ooo \t \xhh \v '\0' 0 '\0' 0 0 #define MAXLINE 1000 char line[maxline+1]; #define LEAP 1 /* int days[31+28+leap ]; 0 "I am a string" "" /* \" "hello," " world"

30 30 C "hello, world" '\0' C strlen(s) s '\ 0 ' /* strlen s int strlen(char s[]) int i; i = 0; while (s[i]!= '\0') ++i; return i; s t r l e n < s t r i n g. h > ' x ' " x " x '\ 0 ' enum boolean NO, YES ; e n u m 0 1 enum escapes BELL = '\a', BACKSPACE = '\b', TAB = '\t', NEWLINE = '\n', VTAB = '\v', RETURN = '\r' ; enum months JAN = 1, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC ; /* FEB 2 MAR 3 # d e f i n e e n u m # d e f i n e 2.4

31 2 31 int lower, upper, step; char c, line [1000]; int lower int upper; int step; char c; char line [1000]; char esc = '\\'; int i = 0; int limit =MAXLINE+1; float eps = 1.0e-5; 0 c o n s t c o n s t const double e = ; const char msg [ ] = "warning:"; c o n s t int strlen(const char[]); c o n s t * / % x % y x y x x % y if ( (year % 4 == 0 && year % 100!= 0) year % 400 == 0 ) printf( "%d is a leap year\n", year ); else printf("%d is not a leap year\n", year );

32 32 C % f l o a t d o u b l e * / % > >= < <= ==!= i < lim -1 i < (lim - 1) && && C g e t l i n e for ( i = 0; i < lim -1 &&(c = getchar())!= '\n' && c!= EOF; ++i ) s[i] = c; s i < lim 1 i < lim g e t c h a r c E O F c && i < lim - 1 && (c = getchar())!= '\n' && c!= EOF! = (c = getchar())!= '\n' c '\n' 1 0! 0 0 1

33 2 33 if (!valid ) if ( valid == 0 )! v a l i d 2-2 && f o r 2.7 f + i i f l o a t c h a r c h a a t o i /* atoi s int atoi( char s[]) int i, n; n = 0; for ( i = 0; s[i] >= '0' && s[i] <= '9'; ++i ) n = 10 * n + (s[i] - '0'); return n; s[i] - '0' s [ i ] ' 0 ' ' 1 ' '2' l o w e r A S C I I l o w e r /* lower c ASCII int lower (int c) if (c >= 'A' && c<= 'Z' ) return c + 'a' - 'A'; else

34 34 C return c; A S C I I A S C I I A Z E B C D I C E B C D I C B < c t y p e. h > t o l o w e r ( c ) c t o l o w e r l o w e r c >= '0' && c<= '9' isdigit(c) < c t y p e. h > C c h a r c h a r i n t 1 0 C c h a r s i g n e d u n s i g n e d i > j && 1 0 d = c >= '0' && c <= '9' c d 1 d 0 i s d i g i t 0 i f w h i l e f o r 0 + * A. 6 long double long d o u b l e d o u b l f l o a t f l o a c h a r s h o r t i n l o n g l o n

35 2 35 f l o a t d o u b l e < m a t h. h > f l o a t u n s i g n e d i n t 16 l o n g 32 1L < 1U i n t 1 U signed long 1L > 1UL 1 L unsigned long = int i; char c; i = c; c = i; c x f l o a t i i n t x = i i = x, f l o a t i n t d o u b l e f l o a t c h a r s h o r t i n f l o a t d o u b l e c h a r f l o a t i n t d o u b l e s q r t d o u b l e s q r t < m a t h. h > n sqrt ( (double) n)

36 36 C n s q r t n d o u b l e n n s q r t double sqrt(double); root = sqrt(2); d o u b l e 2. 0 r a n d s r a n d unsigned long int next = 1; /* rand 0~32767 int rand(void) next = next * ; return (unsigned int)(next/65536) % 32768; /* srand rand() void srand(unsigned int seed) next = seed; 2-3 h t o i ( s ) 0 x 0 X 0 ~ 9 a ~ f A ~ F 2.8 C if (c == '\n') ++nl; n n + + n 1 ++n n n 1

37 2 37 n++ n n n n + + n x = n++ x 5 x = ++n x n (i + j)++ 1 if (c == '\n') nl++; + + s q u e e z e ( s, c ) s c /* squeeze s c void squeeze(char s[], int c) int i, j; for (i = j = 0; s[i]!= '\0'; i++) if (s[i]!= c) s[j++] = s[i]; s[j] = '\0'; c j 1 i f if (s[i]!= c) s[j] = s[i]; j++; g e t l i n e i f if (c == '\n') s[i] = c; ++i; i f if (c == '\n') s[i++] = c;

38 38 C s t r c a t ( s, t ) t s s t r c a t s /* strcat t s s void strcat(char s[], char t[]) int i, j; i = j = 0; while (s[i]!= '\0') /* s i++; while ( (s[i++] = t[j++])!= '\0') /* t ; t s ++ i j 2-4 s q u e e z e ( s 1, s 2 ) s 1 s a n y ( s 1, s 2 ) s 2 s 1 s 1 s 2 1 s t r p b r k 2.9 C c h a r s h o r t i n t l o n g & AND OR ^ XOR << >> ~ & n = n & 0177; n 7 0 x = x SET_ON; x S E T _ O N 1 ^ 1 0 & &&

39 2 39 x 1 y 2 x & y 0 x && y 1 < < > > x << 2 x ~ x = x & ~ 077 x 0 x & ~ 077 x & x 1 6 ~ 077 getbits(x, p, n) x p n 0 n p getbits(x, 4, 3) /* getbits p n unsigned getbits(unsigned x, int p, int n) return (x >> (p+1-n) ) & ~ ( ~ 0 << n); x >> (p+1 n) ~ 0 1 ~ 0 << n ~ 0 n 0 n setbits(x, p, n, y) x p n y n 2-7 invert(x, p, n) x p n rightrot (x, n) x n 2.10 i = i +2 i += 2 + = = * = / = % = > > = < < = & = ^ =! = =

40 40 C += o p= o p + - * / % << >> & ^ op, = 2 = ( ) op ( ) x *= y + 1 x = x * (y + 1) x = x * y + 1 b i t c o u n t 1 /* bitcount x 1 int bitcount (unsigned x ) int b; for ( b = 0; x!= 0; x >>= 1) if ( x & 01 ) b++; return b; x x 0 2 i 2 i 2 i i += 2 i = i + 2 yyval [ yypv [ p3 + p4 ] + yypv [ p1 + p2 ] ] += 2 ANSI C

41 2 41 while ( ( c = getchar( ) )!= EOF) + = = 2-9 x &= ( x 1 ) x 1 b i t c o u n t if (a > b) z = a; else z = b; a b z? :? : z = (a > b)? a : b; /* z = max(a, b) 2 3 f f l o a t n i n t (n > 0)? f : n f l o a t n?: n 10 for (i = 0; i<n; i++) printf("%6d%c", a[i], (i % 10 == 9 i == n - 1)? '\n' : ' '); 10 n i f - e l s e printf("you have %d item%s.\n", n, n == 1? "" : "s"); 2-10 l o w e r i f -

42 42 C e l s e * / % + ( ) >. 6 s i z e o f 5 * & 3, 2-1 ( ) [ ] >.! ~ ++ + * & ( ) sizeof * / % + << >> < <= > >= ==!= & ^ & &? : = += = *= /= %= &= ^= = <<= >>=, + * & ^ ==!= if ( (x & MASK) == 0) C &&? : x = f( ) + g( ); f( ) g( ) g( ) f g x printf("%d %d\n", ++n, power(2,n) ); /*

43 2 43 n p o w e r ++n; printf("%d %d\n", n, power(2,n) ); a[i] = i++; i C p r i n t f

44 C x =0 i + + printf (...) ; x = 0; i++; printf( ); C P a s c a l i f e l s e w h i l e f o r if-else i f - e l s e if ( ) 1 else 2 e l s e i f e l s e 2 i f

45 3 45 if ( ) if (!= 0 ) i f - e l s e e l s e i f e l s e e l s e e l s i f if ( n > 0 ) if ( a > b ) z = a; else z = b; e l s e i f e l s e i f if ( n > 0 ) if ( a > b ) z = a; else z = b; if ( n >= 0 ) for ( i = 0; i < n; i++ ) if ( s[i] > 0) printf ( " " ); return i; else /* printf ( "error -- n is negative\n" ); e l s e i f i if ( a > b ) z = a; else z = b; z = a i f z = a 3.3 else-if C

46 46 C if ( ) else if ( ) else if ( ) else if ( ) else i f e l s e else v x v x x v 0 ~ n 1 x v x x /* binsearch v[0]<=v[1]<=v[2]<= <=v[n-1] x int binsearch ( int x, int v[ ], int n ) int low, high, mid; low = 0; high = n - 1; while ( low <= high ) mid = ( low + high ) / 2; if ( x < v[mid] ) high = mid - 1; else if ( x > v[mid] ) low = mid + 1; else /* return mid; return -1; /*

47 3 47 x v [ m i d ] e l s e - i f 3-1 w h i l e 3.4 switch s w i t c h switch ( ) case : case : default: d e f a u l t d e f a u l t d e f a u l t s w i t c h d e f a u l t 1 i f else if e l s e s w i t c h #include <stdio.h> main ( ) /* int c, i, nwhite, nother, ndigit[10]; nwhite = nother = 0; for ( i = 0; i < 10, i++ ) ndigit[i] = 0; while ( ( c = getchar ( ) )!= EOF ) switch ( c ) case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': ndigit[c - '0']++; break; case ' ': case '\n': case '\t': nwhite++; break; default: nother++; break;

48 48 C printf ( "digits = " ); for ( i = 0; i < 10, i++ ) printf ( " %d", ndigit[i] ); printf ( ", white space = %d, other = %d\n", nwhite, nother ); return 0; b r e a k s w i t c h s w i t c c a s e c a s e c a s s w i t c h b r e a k r e t u r n b r e a k w h i l e f o r d o b r e a k s w i t c h d e f a u l t b r e a k s w i t c h 3-2 escape (s, t) t s \ n \ t s w i t c h 3.5 while f o r w h i l e f o r w h i l e while ( ) 0 f o r for ( ; ; ) while ( ) 2 3 c o n t i n e 3. 7

49 3 49 f o r w h i l e 1 3 f o r 2 2 for ( ; ; ) b r e a k r e t u r n w h i l e f o r while ( ( c = getchar ( ) ) == ' ' c == '\n' c == '\t' ) ; /* w h i l e f o r for ( i = 0; i < n; i++ ) C n F O RT R A N D O P a s c a l f o r C i f o r f o r f o r a t o i 2 4 a t o f #include <ctype.h> /* atoi s 2 int atoi ( char s[ ]) int i, n, sign;

50 50 C for ( i = 0; isspace ( s[i] ); i++ ) ; sign = ( s[i] == '-' )? -1 : 1; if (s[i] == '+' s[i] == '-' ) i++; for ( n = 0; isdigit ( s[i] ); i++) n = 10 * n + (s[i] - '0' ); return sign * n; /* /* s t r t o l B. 5 S h e l l D. L. Shell /* shellsort v[0] v[1] v[n-1] void shellsort ( int v[ ], int n ) int gap, i, j, temp; for ( gap = n/2; gap > 0; gap /= 2 ) for ( i = gap; i < n; i++ ) for ( j = i-gap; j >= 0 && v[j] > v[j+gap]; j -= gap ) temp = v[j]; v[j] = v[j+gap]; v[j+gap] = temp; f o r f o r n / 2 0 f o r f o g a p g a 1 f o r C, f o r f o r reverse ( s ) s #include <string.h> /* reverse s void reverse ( char s[ ] ) int c, i, j;

51 3 51 for ( i = 0, j =strlen(s) - 1; i < j; i++, j-- ) c = s[i]; s[i] = s[j]; s[j] = c; r e v e r s e f o r r e v e r s e for ( i = 0, j =strlen(s) - 1; i < j; i++, j-- ) c = s[i], s[i] = s[j], s[j] = c; 3-3 expand(s1, s2) s 1 a z s 2 a b c x y z a - b - c a - z a - z 3.6 do-while 1 w h i l e f o r C d o - w h i l e d o - w h i l e do while ( ) d o - w h i l e d o - w h i l e P a s c a l r e p e a t - u n t i l d o - w h i l e w h i l f o r d o - w h i l e i t o a i t o a a t o i /* itoa n s void itoa ( int n, char s[ ] ); int i, sign; if ( ( sign = n ) < 0 ) n = -n; i = 0; /* /* n

52 52 C do s[i++] = n % 10 + '0'; /* /* while ( (n /= 10) > 0); /* if (sign < 0) s[i++] = '-'; s[i] = '\0'; reverse(s); n 0 s d o - w h i l e d o - w h i l e d o - w h i l w h i l e 3-4 i t o a n ( 2 1 ) 3-5 itob(n, s, b) n b c itob(n, s, 16) n s 3-6 i t o a 3.7 break c o n t i n u e b r e a k f o r w h i l e d o - w h i l e s w i t c h b r e a k s w i t c h t r i m b r e a k /* trim int trim(char s[]); int n; for (n = strlen(s)-1; n >= 0; n--) if (s[n]!= ' ' && s[n]!= '\t' && s[n]!= '\n') break; s[n+1] = '\n'; return n; s t r l e n f o r n

53 3 53 c o n t i n u e b r e a k c o n t i n u e f o r w h i l e d o - w h i l e w h i l e d o - w h i l e c o n t i n u e f o r c o n t i n u e c o n t i n u s w i t c h c o n t i n u e s w i t c h c o n t i n u e a for (i =0; i < n; i++) if (a[i] < 0) /* continue; /* c o n t i n u e c o n t i n u e 3.8 goto C g o t o g o t o g o t o g o t g o t o b r e a k g o t o for ( ) for ( ) error: if (disaster) goto error; g o t o a b for (i = 0; i < n; i++) for (j = 0; j < m; j++) if (a[i] == b[j])

54 54 C goto found; /* found: /* a[i] ==b[j] g o t o g o t found = 0; for (i = 0; i < n &&!found; i++) for (j = 0; j < m &&!found; j++) if (a[i] == b[j]) found = 1; if (found) /* a[i-1] ==b[j-1] else /* g o t o g o t g o t o

55 C 4 C ANSI C C 1 C ANSI C ANSI C C 4.1 U N I X g r e p o u l d Ah Love! could you and I with Fate conspire To grasp this sorry Scheme of Things entire, Would not we shatter it to bits -- and then Re-mould it nearer to the Heart's Desire! Ah Love! could you and I with Fate conspire Would not we shatter it to bits -- and then Re-mould it nearer to the Heart's Desire!

56 56 C while ( ) if ( ) m a i n g e t l i n e 1 p r i n t f strindex(s, t) t s s t 1 C s t r i n d e x s t r s t r s t r i n d e x 5 g e t l i n e 1 #include <stdio.h> #define MAXLINE 100 /* int getline (char line[ ], int max); int strindex(char source[ ], char searchfor[ ]); char pattern[] = "ould"; /* /* main ( ) char line[maxline]; int found = 0; while ( getline(line, MAXLINE) > 0 ) if ( strindex(line, pattern) >= 0 ) printf( "%s", line); found++; return found; /* getline s int getline(char s[ ], int lim)

57 4 57 int c, i; i = 0; while ( -- lim > 0&& ( c = getchar() )!= EOF && c!= '\n' ) s[i++] = c; if (c == '\n' ) s[i++] = c; s[i] = '\0'; return i; /* strindex t s -1 int strindex(char s[], char t[] ) int i, j, k; for ( i = 0; s[i]!= '\0'; i++ ) for ( j =i, k = 0; t[k]!= '\0' && s[j] ==t[k]; j++, k++ ) ; if ( k > 0 && t[k] == '\0' ) return i; return -1; dummy( ) i n t r e t u r n r e t u r return r e t u r n r e t u r

58 58 C m a i n C U N I X 1 c c m a i n. c g e t l i n e. c s t r i n d e x. c cc main.c getline.c strindex.c m a i n. o g e t l i n e. o s t r i n d e x. o a. o u t m a i n. c cc main.c getline.o strindex.o m a i n. c g e t l i n e. o s t r i n d e x. o c c. c. o 4-1 strrindex(s, t) t s t v o i d i n t s q r t s i n c o s d o u b l e a t o f ( s ) s a t o f a t o i 2 3 a t o i a t o f a t o f < s t d l i b. h > a t o f i n t #include <ctype.h> /* s double atof( char s[ ]) double val, power; int i, sign; for ( i = 0; isspace(s[i]); i++ ) ; sign = (s[i] == '-' )? -1 : 1; /*

59 4 59 if ( s[i] == '+' s[i] == '-' ) i++; for (val = 0.0; isdigit(s[i]); i++) val = 10.0 * val +(s[i] -'0' ); if (s [i] ] = = '.') i++; for ( power = 1.0; isdigit(s[i]); i++) val = 10.0 * val +(s[i] -'0' ); power *= 10.0; return sign * val / power; a t o f a t o f #include <stdio.h> #define MAXLINE 100 /* main ( ) double sum, atof ( char [ ] ); char line[maxline]; int getline(char line[], int max); sum =0; while ( getline(line, MAXLINE) > 0 ) printf( "\t%g\n", sum += atof(line) ); return 0; double sum, atof ( char [ ] ); sum double atof char[ ] double a t o f a t o f m a i n a t o f a t o f d o u b l e m a i n i n t sum += atof(line) i n t

60 60 C double atof ( ); a t o f C v o i d a t o f a t o i /* atoi atof s int atoi( char s[ ] ) double atof(char s[ ]); return (int) atof ( s ); r e t u r n r e t u r return a t o f a t o i r e t u r n return atof ( s ); 4-2 a t o f e-6 e E 4.3 C e x t e r n a l i n t e r n a l i n t e r n a l C F O RT R A N C O M M O N P a s c a l

61 * / F o r t h P o s t s c r i p t (1-2) * (4 + 5) * while ( ) if ( ) else if ( ) else if ( ) else

62 62 C m a i n m a i n p u s h p o p m a i n #include #define main main() push pop void push ( double f ) double pop(void) int getop(char s[ ]) getop m a i n s w i t c h s w i t c h 3. 4 #include <stdio.h> #include <stdlib.h> /* atof() #define MAXOP 100 /* #define NUMBER '0' /* int getop ( char [ ] ); void push ( double f ); double pop(void); /* main ( ) int type; double op2; char s[maxop]; while ( ( type = getop(s) )!= EOF ) switch ( type ) case NUMBER: push(atof(s)); break;

63 4 63 case '+': push ( pop() + pop()); break; case '*': push ( pop() * pop()); break; case '-': op2 = pop( ); push ( pop() - op2); break; case '/': op2 = pop( ); if ( op2!= 0 ) push ( pop() / op2 ); else printf ( "error: zero divisor\n" ); break; case '\n': printf ( "\t%.8g\n", pop( ) ); break; default: printf ( "error: unknown command %s\n", s); break; return 0; + * / push ( pop() - pop() ); /* p o p m a i n #define MAXVAL 100 /* val int sp = 0; double val[maxval]; /* /* /* push f void push ( double f ) if ( sp < MAXVAL ) val[sp++] = f; else printf ( "error: stack full, can't push %g\n", f);

64 64 C /* pop double pop(void); if ( sp > 0 ) return val[--sp]; else printf ( "error: stack empty\n" ); return 0.0; p u s h p o p m a i n g e t o p N U M B E R #include <ctype.h> int getch(void); void ungetch(int); /* getop int getop(char s[ ] ) int i, c; while ( (s[0] = c = getch() ) == ' ' c == '\t' ) ; s[1] = '\0'; if (!isdigit( c ) && c!= '.' ) return c; /* i = 0; if ( isdigit( c ) ) /* while ( isdigit(s[++i] = c = getch( ) ) ) ; if (c == '.' ) /* while ( isdigit(s[++i] = c = getch( ) ) ) ; s[i] = '\0'; if (c!= EOF ) ungetch( c ); return NUMBER; g e t c h u n g e t c h

65 4 65 g e t c h u n g e t c h g e t c u n g e t c h u n g e t c h g e t c h g e t c h a r g e t c h u n g e t c h g e t c h u n g e t c h #define BUFSIZE 100 char buf[bufsize]; int bufp = 0; /* unget /* buf int getch(void) /* return ( bufp > 0 )? buf[--bufp] : getchar( ); void ungetch(int c) /* if ( bufp >= BUFSIZE ) printf ( "ungetch: too many characters\n" ); else buf[bufp++] = c; u n g e t c % s i n e x p p o w B. 4 < m a t h. h >

66 66 C 4-7 u n g e t s ( s ) u n g e t s b u f b u f p u n g e t c h 4-8 g e t c h u n g e t c h 4-9 g e t c h u n g e t c h E O F E O 4-10 g e t l i n e g e t c h u n g e t s 4.4 C m a i n s p v a l p u s h p o p main( ) int sp = 0; double val[maxval]; void push( double f ) double pop( void ) p u s h p o p s p v a l m a i n p u s h p o p m a i n e x t e r n

67 4 67 int sp; double val[maxval]; s p v a l extern int sp; extern double val[maxval]; s p i n t v a l d o u b l e e x t e r n e x t e r e x t e r n p u s h p o p v a l s p file1 extern int sp; extern double val [ ]; void push( double f ) double pop( void ) file2 int sp = 0; double val[maxval]; f i l e 1 e x t e r n f i l e 1 s p v a l 4.5 m a i n m a i n. c p u s h p o p s t a c k. c g e t o p g e t o p. c g e t c h u n g e t c h g e t c h. c c a l c. h # i n c l u d e # i n c l u d e calc.h

68 68 C #define NUMBER '0' void push( double ); double pop( void ); int getop( char [ ] ); int getch( void); void ungetch( int ); main.c #include <stdio.h> #include <stdlib.h> #include "calc.h" #define MAXOP 100 main( ) getop.c #include <stdio.h> #include <ctype.h> #include "calc.h" getop( ) getch.c #include <stdio.h> #define BUFSIZE 100 char buf[bufsize]; int bufp = 0; int getch( void ) void ungetch( int) stack.c #include <stdio.h> #include "calc.h" #define MAXVAL 100 int sp = 0;

69 4 69 double val[maxval]; void push( double ) double pop( void) 4.6 s t a c k. c s p v a l g e t c h. c buf b u f p s t a t i c s t a t i c b u f b u f p g e t c h - u n g e t c h g e t c h u n g e t c g e t c h u n g e t c h s t a t i c static char buf[bufsize]; static int bufp = 0; /* ungetch /* buf int getch( void ) void ungetch( int c) b u f b u f p s p v a l p u s h p o p s t a t i c s t a t i c

70 70 C 4-11 g e t o p u n g e t c h 4.7 r e g i s t e r r e g i s t e r register int x; register char c; f( register unsigned m, register long n ) register int i; C P a s c a l if ( n > 0 ) int i; /* i for ( i = 0; i < n; i++ ) i i f i int x;

71 4 71 int y; f ( double x ) double y; f x d o u b l e f i n t y int x = 1; char squote = '\''; long day = 1000L * 60L *60L * 24L; /* 3. 3 int binsearch( int x, int v[ ], int n ) int low = 0; int high = n - 1; int mid; int low, high, mid; low = 0; high = n - 1;

72 72 C d a y s int days[ ] = 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ; 12 0 char pattern [] = "ould"; char pattern [] = 'o', 'u', 'l', 'd', '\0' ; 5 4 '\ 0 ' 4.10 C 3. 6 i t o a p r i n t d #include <stdio.h> /* printd n void printd(int n ) if ( n < 0 ) putchar( '-' ); n = -n; if ( n / 10 ) printd( n / 10 ); putchar( n % 10 + '0' );

73 4 73 printd (123) p r i n t d n = p r i n t d 1 p r i n t d p r i n t C. A. R. Hoare /* qsort v[left] v[right] void qsort( int v[], int left, int right ) int i, last; void swap( int v[], int i, int j ); if ( left >= right ) return; swap( v, left, (left + right)/2 ); last = left; for ( i = left+1; i <= right; i++ ) if ( v[i] < v[left] ) swap( v, ++last, i ); swap( v, left, right ); qsort( v, left, last-1 ); qsort( v, last+1, right ); /* /* v[0] /* /* s w a p q s o r t /* swap v[i] v[j] void swap( int v[], int i, int j ) int temp; temp = v[i]; v[i] = v[j]; v[j] = temp; q s o r t

74 74 C p r i n t d i t o a 4-13 reverse( s ) s C C # i n c l u d e # d e f i n e # i n c l u d e # d e f i n #include " " #include < > < > # i n c l u d e # i n c l u d e # d e f i n e e x t e r n < s t d i o. h > # i n c l u d e # d e f i n e #define # d e f i n e # d e f i n e \ # d e f i n e Y E S printf ( "YES" ) Y E S M A N

75 4 75 #define forever for ( ; ; ) /* f o r e v e r #define max( A, B ) ( ( A ) > ( B )? ( A ) : ( B ) ) m a x m a x A B x = max( p+q, r+s ); x = ( ( p+q ) > ( r+s )? ( p+q ) : ( r+s ) ); m a x m a x max( i++, j++ ) /* #define square( x ) x * x /* square( z + 1 ) < s t d i o. h > g e t c h a r p u t c h a r < c t y p e. h > # u n d e f #undef getchar int getchar( void ) # #define dprint( expr ) printf( #expr " = %g\n", expr ) dprint( x/y ); printf( "x/y" " = %g\n", x/y );

76 76 C printf( "x/y = %g\n", x/y ); " \" \ \\ ## # ## p a s t e #define paste( front, back ) front ## back paste(name, 1) n a m e 1 ## A 4-14 swap(t, x, y) t # i f s i z e o f 0 # e n d i f # e l i f # e l s e # e l i f i f else if # i f d e f i n e d ( ) 1 0 h d r. h #if!defined( HDR ) #define HDR /* hdr.h #endif # i f # e n d i f H D R # e n d i f S Y S T E M #if SYSTEM == SYSV #define HDR "sysv.h" #elif SYSTEM == BSD #define HDR "bsd.h" #elif SYSTEM == MSDOS #define HDR "msdos.h" #else #define HDR "default.h"

77 4 77 #endif # include HDR # i f d e f # i f n d e f # i f d e f # i f #ifdef HDR #define HDR /* hdr.h #endif

78 C 5 C g o t o ANSI C ANSI C void ( v o i d ) char * 5.1 ( ) c c h a r p c 5-1 & p = &c; c p p c & * x y i p

79 5 79 & * : int x = 1, y = 2, z[10]; int *ip; /* ip ip = &x; y = *ip; *ip = 0; ip = &z[0]; /* ip x /* y 1 /* x 0 /* ip z[0] x y z i p int *ip; *i p i n t double *dp, atof(char *); * d p a t o f ( s ) d o u b l e a t o f c h a r ( v o i d ) i p x x * ip *ip = *ip + 10; * ip 10 * & y = * ip + 1 i p 1 y * ip += 1 i p 1 ++*ip (*ip) ++ * i p i i p * + + i q iq = ip i p i q i i p

80 80 C 5.2 C s w a p swap(a, b); s w a p void swap(int x, int y) /* / int temp; temp = x; x = y ; y = temp; s w a p a b a b s w a p swap(&a, &b); & & a s w a p void swap(int * px, int * py) /* *px *py int temp; temp = *px; *px = *py; *py = temp; 5-2 g e t i n t g e t i n t 5-2 E O F ( ) g e t i n t s c a n f 7. 4 swap g e t i n t

81 5 81 int n, array[size] getint(int *); for ( n = 0; n< SIZE && getint(&array[n])!=eof n++) ; g e t i n t a r r a y [ n ] n 1 a r r a y [ n ] g e t i n t g e t i n t g e t i n t E O F 0 #include <ctype.h> int getch(void); void ungetch(int); /* getint: *pn int getint(int *pn) int c, sign; while (isspace(c = getch( ))) /* ; if (!isdigit(c) && c!= EOF && c!= '+' && c!='-') ungetch(c); /* return 0; sign = ( c = = '-' )? -1 : 1; if (c = = '+' c = = '-') c = getch( ); for (*pn = 0; isdigit(c); c = getch( )) *pn = 10 * * pn + (c - '0'); *pn *= sign; if (c!= EOF ) ungetch(c); return c; g e t i n t * p n g e t c h u n g e t c h ( 4. 3 ) g e t i n t 5-1 g e t i n t g e t i n t g e t f l o a t g e t f l o a 5.3 C

82 82 C int a[10] ; 1 0 a 1 0 a [ 0 ] a [ 1 ]... a [ 9 ] a [ i ] i p a int *pa; pa = &a[0] p a 0 p a a [ 0 ] 5-4 x = *pa; a [ 0 ] x 5-4 p a pa + 1 p p a + i p a i pa i p a i p a a [ 0 ] *(pa+1) a [ 1 ] p a + i a [ i ] *(pa+i) a [ i ] a 1 p a + 1 p a p a + i p i

83 pa = &a[0]; p a a 0 pa = &a[0] pa = a; a [ i ] *( a + i ) a [ i ] C *( a + i ) & & a [ i ] a + i a + i a i p a p a p a [ i ] * ( p a + i ) C pa = a p a + + a = pa a + s t r l e n /* strlen: s int strlen(char *s) int n; for (n = 0; *s!= '\0'; s++) n++; return n; s s + + s t r l e n s t r l e n strlen("hello, word"); strlen(array); strlen(ptr); char s[ ]; char *s; /* /* array 100 /* ptr

84 84 C a f ( &a[2] ) f ( a+2 ) a [ 2 ] f f f ( int arr[ ] )... f ( int *arr )... f p [ 1 ] p [ 2 ] p [ 0 ] 5.4 p p + + p p + = i p p i C a l l o c ( n ) n a l l o c a f r e e ( p ) a f r e e a l l o c a l l o c a f r e e m a l l o c f r e e 8. 7 a l l o c a l l o c b u f a l l o c f r e e a l l o c f r e e a l l o c f r e e s t a t i c m a l l o c a l l o c b u f a l l o c p a l l o c b u f a l l o c n a l l o c a l l o c b u f a l l o c a l l o c p

85 5 85 ) a l l o c p n a l l o c 0 p a l l o c b u f afree(p) a l l o c p 5-6 alloc alloc 5-6 #define ALLOCSIZE /* static char allocbuf[allocsize]; static char *allocp = allocbuf; /* alloc /* char *alloc(int n) /* n if (allocbuf + ALLOCSIZE - allocp >= n ) /* allocp += n; return allocp - n; /* else /* return 0; void afree(char *p) /* p if (p >= allocbuf && p <allocbuf + ALLOCSIZE) allocp = p; 0 static char *allocp = allocbuf; a l l o c p a l l o c b u f static char *allocp = &allocbuf[0]; 0 if ( allocbuf + ALLOCSIZE - allocp >= n ) /*

86 86 C n a l l o c p a l l o c b u f 1 a l l o c ) a l l o c C N U L L 0 NULL < s t d i o. h > N U L L if (allocbuf + ALLOCSIZE - allocp >= n) if (p >= allocbuf && p < allocbuf + ALLOCSIZE) p q = =! = < >= p q p < q 0 ( ) p + n p n p p + n n p p i n t n 4 p q p < q p + 1 p q s t r l e n /* strlen: s int strlen(char *s) char *p = s; while (*p!= '\0') p++; return p - s; p s w h i l e '\ 0 ' p p + + p p s

87 5 87 p ( < s t d d e f. h > p t r d i ff _ t s i z e _ t s t r l e n s i z e _ t s i z e o f ) p p + + p a l l o c a f r e e c h a r f l o a t 0 0 v o i d * 5.5 "I am a string" '\0' 1 printf("hello, world\n "); p r i n t f p m e s s a g e char *pmessage; pmessage = "now is the time"; p m e s s a g e C char amessage[ ] = "now is the time"; /* char *pmessage = "now is the time"; /* a m e s s a g e '/0' a m e s s a g e p m e s s a g

88 88 C strcpy(s, t) t s s = t s t r c p y 1 /* strcpy: t s void strcpy(char *s, char *t) int i; i = 0; while ((s[i] = t[i])!= '\0') i++; s t r c p y /* strcpy: t s 1 void strcpy(char *s, char *t) while ((* s = * t)!= '\0') s++; t++; s t r c p y s t t '\0' s s t r c p y /* strcpy: t s 2 void strcpy(char *s, char *t) while ((*s++ = *t++)!= '\0') ; s t * t + + t t s s '/0'

89 5 89 t s t '\0' ( ) '\ 0 ' 0 /* strcpy: t s 3 void strcpy(char *s, char *t) while (*s++ = *t++) ; C ( < s t r i n g. h > ) s t r c p y strcmp(s, t) s t s t 0 s t /* strcmp: s t 0 int strcmp(char *s, char *t) int i; for (i = 0; s[i] = = t[i]; i++) if (s[i] = = '\0') return 0; return s[i] - t[i]; s t r c m p : /* strcmp: s t 0 int strcmp(char *s, char *t) for (;*s = = *t; s++, t++) if (*s = = '\0') return 0; return *s - *t; + + * + *--p p p *p++ = val; val = *--p; /* val /* val

90 90 C 4. 3 < s t r i n g. h > s t r c a t strcat(s, t) t s 5-4 strend (s, t): t s s t r n c p y s t r n c a t s t r n c m p n strncpy(s, t, n) t n s B 5-6 g e t l i n e ( 1 4 ) a t o i i t o a ( ) r e v e r s e ( 3 ) s t r i n d e x g e t o p ( 4 ) 5.6 U N I X s o r t 3 S h e l l 4 s t r c m p

91 #include <stdio.h> #include <string.h> #define MAXLINES 5000 /* char *lineptr[maxlines]; /* int readlines(char *lineptr[ ], int nlines); void writelines(char *lineptr[ ], int nlines); void qsort(char *lineptr[ ], int left, int right); /* main( ) int nlines; /* if ((nlines = readlines(lineptr, MAXLINES)) >= 0) qsort(lineptr, 0, nlines-1); writelines(lineptr, nlines); return 0; else printf("error: input too big to sort\n"); return 1; #define MAXLEN 1000 /* int getline(char *, int); char *alloc(int); /* readlines: int readlines(char *lineptr[ ], int maxlines) int len, nlines; char *p, line[maxline]; nlines = 0;

92 92 C while ((len = getline(line, MAXLEN)) > 0) if (nlines >= maxlines (p = alloc(len)) = = NULL) return -1; else line[len-1] = '\0'; /* strcpy(p, line); lineptr[nlines++] = p; return nlines; /* writelines: void writelines(char *lineptr[ ], int nlines) int i; for ( i = 0; i < nlines; i++) printf("%s\n", lineptr[i]); g e t l i n e 1. 9 l i n e p t r char *lineptr[maxlines] l i n e p t r M A X L I N E S l i n e p t r [ i ] * l i n e p t r [ i ] i l i n e p t r w r i t e l i n e s /* writelines: void writelines(char *lineptr[ ], int nlines) while (nlines -- > 0) printf("%s\n", *lineptr++); * l i n e p t r * l i n e p t n l i n e 4 s t r c m p /* qsort: v[left]...v[right] void qsort(char * v[ ], int left, int right) int i, last;

93 5 93 void swap(char *v[ ], int i, int j); if (left >= right ) /* 2 return; swap(v, left, (left + right) / 2); last = left; for (i = left + 1; i <= right; i++) if (strcmp(v[i], v[left] < 0) swap(v, ++last, i); swap(v, left, last); qsort(v, left, last - 1); qsort(v, last + 1, right); s w a p /* swap: v[i] v[j] void swap(char *v[ ], int i, int j) char *temp; temp = v[i]; v[i] = v[j]; v[j] = temp; v ( l i n e p t r ) t e m p 5-7 r e a d l i n e s a l l o c 5.7 C d a y _ o f _ y e a r m o n t h _ d a y m o n t h _ d a y month_day(1988, 60, &m, &d); m 2 d 29 ( ) ( 9 30 )

94 94 C 2 static char daytab[2][13] = 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ; /* day_of_year: int day_of_year(int year, int month, int day) int i, leap; leap = year%4 = = 0 && year%100!= 0 year%400 = = 0; for (i = 1; i < month; i++) day += daytab[leap][i]; return day; /* month_day: void month_day(int year, int yearday, int *pmonth, int *pda) int i, leap; leap = year%4 = =0 && year%100!= 0 year%400 = =0; for (i = 1; yearday > daytab[leap][i]; i++) yearday -= daytab[leap][i]; *pmonth = i; *pday = yearday; 0 ( ) 1 ( ) l e a p 0 1 l e a p d a y t a b d a y t a b d a y _ o f _ y e a r m o n t h _ d a y d a y t a b d a y t a b C daytab[i][j] /* [ ][ ] daytab[i, j] /* C d a y t a b 0 1 ~ 12 0 ~ 11

95 d a y t a b f f f(int daytab[2][13])... f(int daytab[ ][13])... f(int (*daytab)[13]) [ ] * int *daytab[13] d a y _ o f _ y e a r m o n t h _ d a y 5.8 m o n t h _ n a m e ( n ) n m o n t h _ n a m e /* month_name: n char * month_name(int n) static char *name[ ] = "Illegal month", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" return ( n < 1 n > 12 )? name[0] : name[n]; n a m e l i n e p t r

96 96 C n a m e i n a m e [ i ] n a m e 5.9 C n a m e int a[10][20]; int *b[10]; a [ 3 ][ 4 ] b [ 3 ][ 4 ] a r o w + c o l a [ r o w ][ c o l ] b 10 b b m o n t h _ n a m e char *name[ ] = "Illegal month", "Jan", "Feb", "Mar"; 5-10 char aname[ ][15] = " Illegal month", "Jan", "Feb", "Mar" ; d a y _ o f _ y e a r m o n t h _ d a y 5.10 C ( a rg c ) ( a rg v )

97 5 97 e c h o echo hello, world hello, world C a rg v [ 0 ] a rg c 1 a rg c 1 a rg c 3 a rg v [ 0 ] a rg v [ 1 ] a rg v [ 2 ] e c h o h e l l o w o r l d a rg v [ 1 ] a rg v [ a rg c 1 ] C a rg v [ a rg c ] 5-11 e c h o 1 a rg v #include <stdio.h> /* 1 main(int argc, char *argv[ ]) int i; for (i = 1; i < argc; i++) printf("%s%s", argv[i], (i < argc -1)? " " : " "); printf("\n"); return 0; 5-11 a rg v 2 a rg v a rg c a rg v #include <stdio.h> /* 2 main(int argc, char *argv[ ]) while (--argc > 0) printf("\n"); return 0; printf("%s%s", argv[i], (i < argc -1)? " " : ""); a rg v ( + + a rg v ) a rg v [ 1 ] a rg v [ 0 ] a rg v a rg a rg c 0 p r i n t f printf((argc > 1)? "%s " : "%s", *++argv);

98 98 C p r i n t f U N I X g r e p #include <stdio.h> #include <string.h> #define MAXLINE 1000 int getline(char *line, int max); /* find: main(int argc, char *argv[ ]) char line[maxline]; int found = 0; if (argc!= 2) printf("usage: find pattern\n"); else while (getline(line, MAXLINE) > 0) if (strstr(line, argv[1])!= NULL) printf("%s", line); found++; return found; strstr(s, t) t s t s < s t r i n g. h > U N I X C x (x e x c e p t ) n (n n u m b e r ) find -x -n find -nx #include <stdio.h>

99 5 99 #include <string.h> #define MAXLINE 1000 int getline(char * line, int max); /* find: main(int argc, char *argv[ ]) char line[maxline]; long lineno = 0; int c, except = 0, number = 0, found = 0; while (- -argc > 0 && (* ++argv)[0] = = '-') while (c = *++argv[0]) switch (0) case 'x': except = 1; break; case 'n': number = 1; break; default: printf("find: illegal option %c\n", c); argc = 0; found = -1; break; if (argc!=1) printf("usage: find -x -n pattern\n"); else while (getline(line, MAXLINE) > 0) lineno++; if ((strstr(line, *argv)!= NULL)!= except) if (number) printf("%d:", lineno); printf("%s", line); found++; return found; a rg c a rg v a rg c a rg v a rg c 1 * a rg v * + + a rg v (* + + a rg v )[ 0 ] ( ** + + a rg v ) [ ] * + +

100 100 C * + + ( a rg v [ 0 ]) * + + a rg v [ 0 ] * + + a rg v [ 0 ] a rg v [ 0 ] 5-10 e x p r expr * 2 (3 + 4) 5-11 e n t a b d e t a b ( 1 ) 5-12 e n t a b d e t a b entab -m +n m n ( ) 5-13 t a i l n 10 tail -n n n C n s t r c m p s t r c m p n u m c m p m a i n q s o r t

101 5 101 #include <stdio.h> #include <string.h> #define MAXLINES 5000 char *lineptr[maxlines]; /* /* int readlines(char *lintptr[ ], int nlines); void writelines(char *lineptr[ ], int nlines); void qsort(void *lineptr[ ], int left, int right, int (*comp) (void *, void *)); int numcmp(char *, char *); /* main(int argc, char *argv[ ]) int nlines; int numeric = 0; /* /* 1 if (argc > 1 && strcmp(argv[1], "-n ") = = 0) numeric = 1; if ((nlines = readlines(lineptr, MAXLINES)) >= 0) qsort((void **) lineptr, 0, nlines-1, (int (*)(void *, void *)) (numeric? numcmp : strcmp)); writelines(lineptr, nlines); return 0; else printf("input too big to sort\n"); return 1; q s o r t s t r c m p n u m c m p & q s o r t q s o r t v o i d * v o i d v o i d * q s o r t v o i d * v o i d /* qsort: v[left]... v[right] void qsort(void *v[ ], int left, int right, int (*comp) (void *, void *)) int i, last; void swap(void *v[ ], int, int);

102 102 C if (left >= right) /* 2 return; swap(v, left, (left + right) / 2); last = left; for (i = left + 1; i <= right; i++) if ((*comp) (v[i], v[left]) < 0) swap(v, ++last, i); swap(v, left, last); qsort(v, left, last - 1, comp); qsort(v, last+1, right, comp); q s o r t int (*comp) (void *, void *) c o m p v o i d * i n t i f if ((*comp) (v[i], v[left]) < 0) c o m p c o m p * c o m (*comp) (v[i], v[left]) int *comp(void *, void *) /* c o m p s t r c m p n u m c m p a t o f #include <stdio.h> /* numcmp: s1 s2 int numcmp(char *s1, char *s2) double v1, v2; v1 = atof(s1); v2 = atof(s2); if (v1 < v2) return -1 ; else if (v1 > v2) return 1; else return 0; s w a p s w a p v[ ] void * void swap(void *v [ ], int i, int j)

103 5 103 void *temp; temp = v[i]' v[i] = v[j]; v[j] = temp; 5-14 r ( ) r n 5-15 f a A 5-16 d f C C int * f( ); /* f: int (*pf) ( ); /* pf: * ( ) t y p e d e f 6. 7 C d c l C char **argv argv: int (*daytab) [13] daytab: 13 int *daytab[13] daytab: 13 void *comp( )

104 104 C comp: void (*comp) ( ) comp: char (*(*x( )) [ ]) ( ) x: char (*(*x[3])( )) [5] x: 3 5 d c l A. 8. 5, : * : ( ) ( ) [ ] * C (*pfa[ ]) ( ) d c l p f a pfa[ ] *pfa[ ] (*pfa[ ]) d c l d c l d i r d c l

105 5 105 /*dcl: void dcl(void) int ns; for (ns = 0; gettoken( ) = = '*'; ) ns++; dirdcl( ); while (ns- - > 0) strcat(out, "pointer to"); /* '*' /* dirdcl: void dirdcl(void) int type if (tokentype = = '(' ) /* ( ) dcl( ); if (tokentype!= ')' ) printf("error: missing ) \n"); else if (tokentype = = NAME) /* strcpy(name, token); else printf("error: expected name or (dcl)\n"); while ((type = gettoken( )) = = PARENS type = = BRAKCETS) if (type = = PARENS) strcat(out, "function returning"); else strcat(out, " array"); strcat (out,token); strcat(out, " of"); d c l c h a r i n t c o n s #include <stdio.h> #include <string.h> #include <ctype.h> #define MAXTOKEN 100

106 106 C enum NAME, PARENS, BRACKETS void dcl(void); void dirdcl(void); int gettoken(void); int tokentype; char token[maxtoken]; char name[maxtoken]; char datatype[maxtoken]; char out[1000]; /* /* /* /* char int /* main( ) while (gettoken( )!= EOF) /* strcpy(datatype, token); out[0] = '\0'; dcl( ); /* /* if (tokentype!= '\n') printf("syntax error\n"); printf("%s: %s %s\n", name, out, datatype); return 0; g e t t o k e n int gettoken(void) int c, getch(void); void ungetch(int); char *p = token; /* while (( c = getch( )) = = ' ' c = = '\t') ; if (c = = '(' ) if (( c = getch)) = = ')') strcpy(token, "( )"); return tokentype = PARENS; else ungetch(c); return tokentype = '('; else if (c = = '[') for (*p++ = c; (*p++ = getch( ))!= ']'; ) ; *p = '\0'; return tokentype = BRACKETS; else if (isalpha(c) for (*p++ = c; isalnum(c = getch( )); )

107 5 107 *p++ = c; *p = '\0'; ungetch(c); return tokentype = NAME; else return tokentype = c; g e t c h u n g e t c h 4 u n d c l x x ( ) * [ ] * ( ) char char (* (* x( ) ) [ ] ) ( ) g e t t o k e n u n d c l d c l /* undcl: main( ) int type; char temp[maxtoken]; while (gettoken( ))!= EOF) strcpy(out, token); while ((type = gettoken( ))!= '\n') if (type = =PARENS type = = BRACKETS) strcat(out, token); else if (type = = '*') sprintf(temp, "(*%s)", out); strcpy(out, temp); else if (type = = NAME) sprintf(temp, "%s %s", token, out); strcpy(out, tmep); else printf("invalid input at %s\n", token); printf("%s\n", out); return 0; 5-18 d c l 5-19 u n d c l 5-20 d c l c o n s t

108 C 6 P a s c a l C ANSI C 6.1 x y x y 6-1 struct point int x; int y; ; s t r u c t s t r u c t 6-1 p o i n t

109 6 109 struct... x, y, z int x, y, z x y z p o i n t struct point pt; p o i n t p t struct point maxpt = 320, 200 ;. p t printf("%d, %d", pt.x, pt.y); (0, 0) p t double dist, sqrt(double); dist = sqrt((double)pt.x * pt.x + (double)pt.y * pt.y); 6-2 struct rect struct point pt1; struct point pt2; ; r e c t p o i n t s c r e e n struct rect screen; screen.pt1.x s c r e e n p t 1 x &

110 110 C m a k e p o i n t p o i n /* makepoint: x y struct point makepoint(int x, int y) struct point temp; temp.x = x; temp.y = y; return temp; m a k e p o i n t struct rect screen; struct point middle; struct point makepoint(int, int); screen.pt1 = makepoint(0, 0); screen.pt2 = makepoint(xmax, YMAX); middle = makepoint((screen.pt1.x + screen.pt2.x) / 2, (screen.pt1.y + screen.pt2.y) / 2); /* addpoint: struct point addpoint(struct point p1, struct point p2) p1.x += p2.x; p1.y += p2.y; return p1; p 1 p t i n r e c t /* ptinrect: p r 1 0 int ptinrect(struct point p, struct rect r) return p.x >= r.pt1.x && p.x < r.pt2.x && p.y >= r.pt1.y && p.y < r.pt2.y; p t 1 p t 2 #define min(a, b) ((a) < (b)? (a) : (b)) #define max(a, b) ((a) > (b)? (a) : (b))

111 6 111 /* canonrect : struct rect canonrect(struct rect r) struct rect temp; temp.pt1.x = min(r.pt1.x, r.pt2.x); temp.pt1.y = min(r.pt1.y, r.pt2.y); temp.pt2.x = max(r.pt1.x, r.pt2.x); temp.pt2.y = max(r.pt1.y, r.pt2.y); return temp ; struct point *pp; p p struct point p p p o i n t p p ( * p p ). x ( * p p ). y p p struct point origin, *pp; pp = &origin; printf ("origin is (%d, %d) \n ", (*pp).x, (*pp).y); (*p p ). x. * *p p. x *( p p. x ) x p p-> > printf("origin is (%d, %d) \n ", pp->x, pp->y);. > struct rect r, *rp = &r; r.pt1.x rp->pt1.x (r.pt1).x (rp->pt1).x. > [ ] struct int len; char *str; *p; ++p->len

112 112 C l e n p > (p->len) (++p)->len p 1 l e n p++ ->len l e n p 1 p > s t r s t r p > s t r + + s t r s t r 1 s + + ( p > s t r ) + + s t r 1 p + + > s t r s t r p C k e y w o r d k e y c o u n t char *keyword[nkeys]; int keycount[nkeys]; char *word; int count; struct key char *word; int count; keytab[nkeys]; k e y k e y t a b k e y t a struct key char *word; int count; ; struct key keytab[nkeys] k e y t a b struct key char *word; int count; keytab[ ] = "auto", 0,

113 6 113 "break", 0, "case", 0, "char", 0, "const", 0, "continue", 0, "default", 0, /* "unsigned", 0, "void", 0, "volatile", 0, "while", 0 ; "auto", 0, "break", 0, "case", 0, [] k e y t a b k e y t a b g e t w o r d 3 #include <stdio.h> #include <ctype.h> #include <string.h> #define MAXWORD 100 int getword ( char *, int ); int binsearch ( char *, struct key *, int ); /* C main ( ) int n; char word[maxword]; while ( getword (word, MAXWORD )!= EOF ) if ( isalpha ( word[0] )) if ( ( n = binsearch ( word, keytab, NKEYS ) ) >= 0 ) keytab[n].count++; for ( n = 0; n < NKEYS; n++ ) if ( keytab[n].count > 0 ) printf ( "%4d %s\n ", keytab[n].count, keytab[n].word ); return 0;

114 114 C /* binsearch: tab[0] tab[n-1] int binsearch ( char *word, struct key tab[ ], int n ) int cond; int low, high, mid; low = 0; high = n-1; while ( low <= high ) mid = ( low + high ) / 2; if ( ( cond = strcmp ( word, tab[mid].word ) ) < 0 ) high = mid - 1; else if ( cond > 0 ) low = mid + 1; else return mid; return -1; g e t w o r d N K E Y S k e y t a b k e y t a b keytab / struct key C s i z e o f sizeof sizeof ( ) s i z e o f s i z e _ t < s t d d e f. h > # d e f i n e N K E Y S #define NKEYS ( sizeof keytab / sizeof ( struct key ) )