C程序设计语言

Transcription

1 C

2 505 1 C B.W.Kernighan, D.M.Ritchie, 2 C 3 C from C Programming Language ---- P ; P20 1-8, 1-9, 1-10; P ; P ; P , 1-22, 1-23; P46 2-3; P49 2-6, 2-8; P58 3-1; P60 3-2; P63 3-3; P64 3-5, 3-6; P71 4-1; P73 4-2; P79 4-4, 4-6, 4-10; P ; P ; P97 5-1, 5-2; P , 5-5; P ; P ; P ; P ; P ,

3 C UNIX C UNIX UNIX Bell Lab K.Thompson D.M.Ritchie 1969 O.S. MIT AE Multies 1970 V1 V2 PDP V3 PDP11/ V4 PDP11/ D.M.Ritchie C C B BCPL CPL 1973 Ritchie Thompson C UNIX 90% V5

4 C 78 C UNIX C C UNIX 78 D.Ritchie C 88 ANSI C C K&R C 88 ANSI C 89 3 CPL BCPL B C C C.Strachey 1969 M.Richards 1970 K.Thompson 1972 D.M.Ritchie 1988 B.Stroustrup

5 C

6 C C C C C

7 1 1 C 1 2 C

8 enum typdef int float char struct union short double long unsigned C

9 { } { } if if else while, do_while, for switch goto, continue, break, return auto static extern register C

10 { } = += *= C 20% 6 C 75%~80% C C C

11 C C PASCAL C

12 1 2 C ,1, 9 a,b, z,a,b, Z _ _ _ + - * / % > < ^ ->. & &&,, >>, <<, =, ==,!=, <=, >=, (, ), [, ],,?, :, {, },,, #, C

13 1.2.2 int auto goto if float static return else char extern break while short register continue for long do unsigned switch double case struct union void enum typedef sizeof const signed default define, undef, include, ifdef, ifndef, endif, line C C

14 1.2.3 C C C main main main C C.C.h C C

15 [ 1-1] /* file: hello.c */ main( ) { printf( hello, world\n ); } /* */ 2. main( ) 3. printf I/O 4. \n C \n \t \b \r \f \\ \ \ \ddd \ PASCAL C

16 [ 1-2] main( ) { /* simple.c */ int a, b, c, sum; a =1; b = 2; } scanf printf scanf( %d, &c); /* */ sum = a + b + c; printf( Sum = %d\n, sum); scanf printf % / %d %d %f %f %c %c %s %s %o %x %% % %d,%f %4d,%6.2f C

17 1.3 C / vi(unix), edit(dos) =>.o.obj.o(.obj) =>.exe C

18 1)UNIX Cc [-o ] [ c] o a.out c.o s1.c, s2.c s3.c C cc c s1.c cc c s2.c cc o s s1.o s2.o s3.c 2)DOS Windows DOS WINDOWS C C VC BC 3 / >, >> C> prog > outfile < C> prog < infile C>prog1 prog2 C

19 C _

20 2 1 2 C [ ] int lower, upper, step; char c, line[100]; extern double x; const double PI = ; const char msg[ ] = Warning ;

21 literal line < 66 ci = * dia; s[i]!= \0 ; #define PAGESIZE 66 #define PI #define ENDSTRING \0 line < PAGESIZE ci = PI * dia; s[i]!= ENDSTRING; \0

22 long 1275, 0127, 0x19a, 0xABD, 123l, 89L , -8E-3, -125e+4 3 A, b,? ASCII IBM EBCDIC ASCII A 65 b \0, \n, \t, \b, \r, \f \\, \, \ddd ( ddd ddd) if( c >= A && c <= Z ) return ( c + a A );

23 4 The C Programming Language \0 0 x x \0

24 UNIX, W32 DOS int short(int) long(int) unsigned(int) float double char 8 8 ANSI C const ---- #define const Volatile ----

25 2 4 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); } main( ) { int n; char st[100]; } scanf( %s, st); n = atoi(st); printf( %d\n, n);

26 C int unsigned

27 4 double float long unsign int short, char

28 cast --- < > < > x = sqrt((double) n );

29 2.5 C < >; C PASCAL E1 = E2 C C a = b = c = 0;

30 2 5 1 < > ::= < > < > < > < > < > < > < > < > ::= < > < > < > < > < >( [< > [, < >]* ]) < >

31 < > ::= < > < >[< >] < >.< > < >->< > (< >) *< >

32 1. < > < > < > ::= * &< > -< > +< > ~< >!< > (< >)< > sizeof < > sizeof (< >) ++< > --< > / < >++ < >-- /

33 [ 1] int x, y; int *px; X: 10 Y: 10 x= 10; px = &x; PX: y = *px; ( y = x) - < > &(3), &(x+5) - < > ++

34 [ 2] n = 5; n = 5; x = ++n; x = n++; n 6,? x: 6? x: 5, n: 6

35 [ 3] #include <stdio.h> main( ) { int a, b, c; a = b = c = 0; a = ++b + ++c; } printf( %d %d %d\n,a, b, c); a = b++ + c++; printf( %d %d %d\n,a, b, c); a = ++b + c++; printf( %d %d %d\n,a, b, c); a = b c; printf( %d %d %d\n,a, b, c); a = ++c + c; printf( %d %d %d\n,a, b, c); /* */ /* */ /* */ /* */ /* */

36 2 < > ::= < > < > > < > ::= * / % + - >> << > < >= <= ==!= & ^ &&, *, /, %, +, - >>, << >, <, >=, <=, ==,!= &, ^, &&,

37 [ ] x p n unsigned getbits(unsigned x, unsigned p, unsigned n) { } return ( ( x >> (p + 1 n)) & ~(~0 << n));

38 A && B A B A 0 B 0 A 0 B 0 >> int unsigned 0 << 0 / % e1,e2 e1 e2 e2 a = (t = 3, t+2); 5

39 3 < > ::= < 1>? < 2> : < 3> if( a > b) else z = a; z = b; z = ( a > b)? a: b;

40 4 < > ::= >< > < > ::= = += -= /= %= *= >>= <<= &= ^= = (e1) op= (e2) op (e1) = (e1) op (e2) x += n; x = x+n; [ ] (e1) op= (e2) e1 (e1)=(e1)op(e2) a[++i] *= n a[++i] = a[++i] * n

41 bfreelist_frow->b_back += 2 x += n x = x+n y *= n+1; y = y*(n+1) y = y*n+1

42 ( ) [ ]. -> 2 -! ~ & * ( ) sizeof 3 * / % << >> 6 < <= >= > 7 ==!= 8 & 9 ^ && 12 13? : 14 *= /= %= += -= <<= >>= &= ^= = 15

43 3 1 C

44 1 *x++ = y *= z+3; ++x; --y; 2 goto break; continue; return; return ( ); 3

45 1 { [< >] < >* } } 2 if if_else 3 for while do_while 4 switch case

46 3 2 F if( ) T if( ) F else T 2

47 if else if( n > 0) if(a >b) else z = a; z = b; else else if else if {} if(n > 0){ } else if(a >b) z = a; z = b;

48 if else if if( ) else if( ) else

49 [ 3-1] #include <stdio.h> main( ) { int a, b; char ch; scanf( %d %d, &a,&b); ch = getchar( ); if( ch = = y ){ int x; x = a; a = b; b = x; printf( a = %d b= %d\n, a, b); } else printf( no swap!\n ); }

50 3.3 while while F T

51 [ 3-2] #define EOF 1 main( ) { int c; while(( c = getchar( ))!= EOF) putchar( c ); }

52 [ 3-3] main( ) { } int x = 3; while(x%3!= 2) x +=2; while(x%5!= 4) x += 6; while(x%6!= 5) x += 30; while(x%7!= 0) x += 30; printf( x = %d\n,x);

53 3.4 for for while 2 { 2 2 T F } 3 3

54 for for( i=0; i<10; i++)

55 [ 3-4] int atoi(char s[ ]) { int i, n, sign; for(i=0; s[i] = = s[i] = = \n s[i] = = \t ; i++) ; /* skip white space */ sign = 1; if(s[i] = = + s[i] = = - ) sign = (s[i++] = = + )?1:-1; for(n=0; s[i] >= 0 && s[i] <= 9 ; i++) n = 10*n + s[i] 0 ; return ( sign * n); }

56 [ 3-5] void reverse(char s[ ]) { int c, i, j; for(i=0, j=strlen(s)-1; i < j ; i++,j--){ c = s[i]; s[i] = s[j]; s[j] = c; } } int strlen(char s[ ]) { int i=0; while(s[i]!= \0 ) ++i; return (i); }

57 [ ] for( ; (c = getchar( ))!= EOF; ) for( ; ;) s; s; 2 break return while(a) B; for(; A; ) B;

58 3.5 do_while do while ( ) F while do_while T

59 while(for) do_while [ ] do_while Pascal Repeat untill --- False True

60 [ 3-6] void itoa(int n, char s[ ]) { } int i, sign; if((sign = n) < 0) n = -n; i = 0; do { s[i++] = n% ; } while( (n /= 10 ) > 0); if(sign < 0) s[i++] = - ; s[i] = \0 ; reverse(s); do_while {} while while

61 for while do_while

62 3 6 (switch) switch ( ) case default

63 switch swich { case 1 1 } case 2 2 case n n default n+1 C1 C2 E Cn default S1 S2 Sn Sn+1 1) 2) case 3) 4) default default

64 [ ] 1) 2) switch 3) default default switch 4) case default pascal case switch break; 5) case C switch Pascal case C default

65 [ ] char score; switch(score) { case E : printf( no pass\n ); break; case D : printf( pass\n ); break; case C : printf( better\n ); break; case B : printf( right\n ); break; case A : printf( all right\n ); break; }

66 3.7 break continue goto ; ; return 1 return; 2 return [ ] 1 main return 2 return

67 goto goto goto goto int i, j, k, x; float y; for(i = ) { for(j = ) { for(k = ) { scanf( %d %f, &x, & y); if(x < 0 && y < 0.0) goto inerr; } } } inerr: printf( error in input data!\n );

68 [ 3-7] #define MAXLINE 1000 int getline(char s[ ], int lim); main( ) { } int n; char line[maxline]; while(( n = getline(line, MAXLINE)) > 0) { } while( --n >= 0) if(line[n]!= && line[n]!= \n && line[n]!= \t ) break; line[n+1] = \0 ; printf( %s\n, line);

69 int getline(char s[ ], int lim) { int c, i; for(i=0; i < (lim-1) && (c = getchar( ))!= EOF && c!= \n ; i++) s[i] = c; if( c = = \n ){ s[i] = c; ++i; } s[i] = \0 ; return (i); }

70 [ 3-8] main( ) { int count; char c; count = 0; while(( c = getchar( ))!= EOF){ if( c >= 0 && c <= 9 ) continue; count++; } printf( non digital character: %d\n, count); }

71 [ 3-9] #include <stdio.h> char input[ ] = SSSWILTECH1\1\11W\1WALLMP1 ; main( ) { int i, c; for( i = 2; (c = input[i])!= \0 ; i++){ } switch ( c ) { case a : case 1 : putchar( i ); continue; break; case 1: while( ( c = input[ ++i])!= \1 && c!= \0 ); case 9: case E : case L : default: putchar( S ); continue; putchar( c ); continue; } } putchar( ); putchar( \n ); SWITCH SWAMP

72 2 for( putchar( 1 ); putchar( 2 ); putchar( 3 )){ putchar( 4 ); continue; putchar( 5 ); }

73 3 while(a) { if(b) contine; C; } while(a) if(!b) C;

74 I/O #include <stdio.h> ( getchar, putchar ) #include <math.h> (sin, cos, sqrt ) A B C D

75 ANSI C { [ ] }

76 main ANSI C int void C Pascal procedure function C [ ] C Pascal

77 [ ] C return

78 [ 4-1] x #include <stdio.h> int power(int x, int n); main( ) { } { int i; for (i=0; i <= 10; ++i) printf( %d %d %d\n, i, power(2, i), power(-3, i)); int power(int x, int n) int i, p; p = 1; for(i=1; i<=n; ++i) p = p*x; return (p); }

79 power int power(int x, int n) { int p; for(p = 1; n > 0; --n) p *= x; return (p); }

80 [ 4-2] #define MAXLINE 1000 int index(char s[ ], char t[ ]); int getline(char line[ ], int ml); main( ) { char line[maxline]; while(getline(line, MAXLINE) > 0) if(index(line, the ) >= 0) printf( %s, line); }

81 int index(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(t[k] = = \0 ) return ( i); } return ( -1); }

82 Now is the time for all good men to come to the aid of their party this is the time men to come to the aid of their party

83 4 2 2 ANSI C void C

84 [ 4-3] double atof(char s[ ]) { double val, power; int i, sign; for(i=0; s[i] = = s[i] = = \n s[i] = = \t ; i++) ; sign = 1; if(s[i] = = + s[i] = = - ) sign = (s[i++] = = + )? 1:-1; for(val = 0; s[i] >= 0 && s[i] <= 9 ; i++) val = 10* val + s[i] 0 ; if(s[i] = =. ) i++; for(power=1; s[i] >= 0 && s[i] <= 9 ; i++) { val = 10*val +s[i] 0 ; power *= 10; } return ( sign * val / power); }

85 4 2 3 prototype ANSI C double atof(char s[ ]); double atof( char * );

86 [ 4-4] #define MAXLINE 100 double atof(char s[ ]); int getline( char line[ ], int maxline); main( ) { double sum; char line[maxline]; sum = 0; while(getline(line, MAXLINE) > 0) printf( \t%.2f\n, sum += atof(line)); } [ ]

87 4 2 4 ANSI C float double char short int C Pascal

88 void swap ( int x, int y) { } { } main( ) int temp; temp = x; x = y; y = temp; int a = 2, b = 3; swap(a, b); a b a=2 b=3 swap(a,b) x=2 y=3 swap x=3 y=2

89 a b void swap ( int *px, int *py) { int temp; temp = *px; *px = *py; *py = temp; } main( ) { int a =2, b = 3; &a &b a b } swap ( &a, &b); px py

90 scanf int, char, double C C

91 4 2 5 C (1) x n = 1 n =0 x * x n-1 n > 0 (2) n! = 1 n =0 n * (n-1)! n > 0

92 [ 4-5] n! #include <stdio.h> int fact(int n); main( ) { printf( 3!=%d, 5!=%d\n, fact(3), fact(5)); } int fact(int n) { fact(3) 3*2*1 if( n <= 1) return ( 1); else 3*fact(2) 2*1 return ( n * fact(n-1)); 2*fact(1) } 1 1

93 fact int fact(int n) { int f = 1; While(n){ f *= n; n--; } return ( f); }

94 [ 4-6] (hanoi tower) void hanoi( int n, char x, char y, char z) { } if( n > 0 ) { } main( ) hanoi(n-1, x, z, y); printf( MOVE %d: %c %c\n, n, x, z); hanoi(n-1, y, x, z); { } int n; printf( Please input the number of hanoi tower: ); scanf( %d, &n); hanoi(n, A, B, C ); A B C

95 4 3 C Pascal

96 4 3 1 [ ] auto static extern auto register

97 1)

98 2 C extern extern extern

99 3) static static private ( C++ )

100 4) register 2~3 int, char, short, unsigned register register &

101

102 binary(int x, int y, int n) { int low = 0; int high = n 1; } ANSI C ( ANSI C int x[ ] = { 1, 3, 3, 3}; static char pattern[ ] = the ; static char pattern[ ] = { t, h, e, \0 };

103

104 4 4 C C f( ) { } g( ) { } C if(n > 0) { } int i; /* declare a new */ for(i=0; i<n; i++)

105 [ 4-7] int i = 0; main( ) { int i = 1; printf( i=%d,, i); { int i = 2; printf( i=%d,, i); { i += 1; printf( i=%d,, i); } printf( i=%d,, i); } printf( i=%d\n, i); }?i=1, i=2, i=3, i=3, i=1

106 4. 5 C #define #undef #include #if #ifdef #ifndef #else #endif #line ( # ) C C C #include #define #if

107 4 5 1 include #include #inlcude < > #define

108 #include.h #include s.c f.h r.h #include f.h #include r.h

109 #include.h #include.h #include <stdio.h> #include <math.h> #include local.h

110 4 5 2 #define #define 1 #define YES 1 #define EOF -1

111 #define := = #define then #define begin { #define end ;} Pascal C if( i > 0) then begin a := 1; b:=2; end

112 2) #define #define max(a, B) ((A) > (B)?(A) : (B)) x = max(p+q, r+s); x = ((p+q) > (r+s)? (p+q) : (r+s)); ( a. max(a,b); b. (A)>(B)?(A) : (B) )

113 #define square( x) x * x square(z+1) z+1*z+1 #define square(x) ((x) * (x))

114 #undef YES

115 4 5 3 C #if #ifdef #ifndef

116 #if #else #endif #ifdef YES #else #endif --YES --YES

117 #ifndef THIS #define THIS #endif

118 4 5 4 #line [ ] #line 100 another_name another_name, line 100

119 C

120 5 1 [ ] [ ] [ ] C C

121 1) int a[50]; a[0] ~ a[49] float m[ c - a ], p[2*sizeof(double)]; a[0] a[1]

122 2) char static char mes[ ] = C Language ; char line[100]; 0 ~ N-1 N \0 1

123 3 float y[4][3]; C C y[i][j] y[i,

124 float y[4][3] = { y[0] = { 1, 3, 5 }; } { 1, 3, 5 }, y[1] = { 2, 4, 6 }; { 2, 4, 6 }, y[2] = { 3, 5, 7 }; { 3, 5, 7 }, y[3] = { 0, 0, 0 }; float y[4][3] = { 1, 3, 5, 2, 4, 6, 3, 5, 7 }; C float y[4][3] = { } {1}, {2}, {3}, {4} y[0] = { 1, 0, 0 }; y[1] = { 2, 0, 0 }; y[2] = { 3, 0, 0 }; y[3] = { 4, 0, 0 };

125 main( ) { } float a[4][3], b[3][4], c[4][4]; fun(a, b, c); void fun(float x[ ][3], float y[ ][4], float z[ ][4]; { }

126 [ 5-1] #define MAXLINE 1000 int getline(char line[ ], int maxline); void copy(char s1[ ], char s2[ ]); main( ) /* find longest line */ { } int len; /* current line length */ int max; /* maximum length seen so far */ char line[maxline]; /* current input line */ char save[maxline]; /* longest line saved */ max = 0; while( ( len = getline(line, MAXLINE)) > 0 ) if( len > max ) { } if( max > 0) max = len; copy(line, save); printf( %s, save);

127 void copy( char s1[ ], char s2[ ]) /* copy s1 t o s2 */ { int i = 0; while( ( s2[i] = s1[i] )!= \0 ) i++; }

128 [ 5-2] int day_of_year(int year, int month, int day) { int i, leap; static int day_tab[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 } }; leap = year % 4 = = 0 && year % 100!= 0 year % 400 = = 0; for(i=1; i < month; i++) day += day_tab[leap][i]; return ( day ); }

129 5.2 C C 0 #define NULL 0 C

130 pi = &i; pi i; y = *pi; pi 0x100 i pi=&i pi 0x100 y=*pi y i

131 int *px; char *pc; char *acp[ ]; char (*pac)[ ]; int f( ); int *fpi( ); int (*pfi)( ); int (*p[4][3])( ); /* */ /* */ /* */ /* */ /* */ /* */ /* */ /* */ int *(*pfpi)( ); /* */

132 int x = 100; int *px; px = &x; px x *px px 100 x *px

133 1 int x = 1; int *px; *px = x; 2 char *string; scanf( %s, string); strcpy(string, Hello ); C

134 malloc alloc &

135 2. 1) p p+n p-n p+1 p++ 2) P1 P2 py = px px py strcpy(py, px) 3) = =, >, < 4) p q q p p p q

136 [ ] mid = (low + high ) /2 low mid = low + (high low)/2 mid high

137 p++ p+1 y = *px + 1 y= *(px + 1) y = (*px)++ y = *px ++

138 1. p++ p p+1 p 2. *px+1 px 1 *(px+1) px 1 y= *px+1 = 101 y= *(px+1) = (*px)++ px 1 *px++ px px 1 px 100 px 101 px px 100 px Y=(*px)++ =100 Y=*px++ = 100

139 5 2 2 C 0

140 int a[10], x; int *pa; pa = &a[0]; x = *pa; x = a[0]; x = *a; x = *(pa + 1); x = a[1]; x = *(a+1); x = *(pa+i); x = a[i]; x = *(a+i); pa = &a[0] pa = a; a[i] = *(a+i) pa =a; a = pa ; a++; pa = &a;

141 printf( %d\n, data[i]); printf( %d\n, *data); data[i] *data i data i x + =>

142 C printf( a constant character string\n ); [ ] char *char_ptr, word[20]; char_ptr = point to me ; word = you can t do this ; word

143 int values[100], *inptr = values, i; &values[0] values intptr values[0] *values *intptr &values[i] values+i intptr+i valuse[i] *(values+i) *(intptr+i), intptr[i] values Values values i+1 Values i+1

144 [ 5-3] strlen 1) int strlen( char s[ ]) { } 2) int strlen(char *s) { } int n; for(n=0; *s!= \0 ; s++) n++; return (n); main( ) int n = 0; char st[100]; while(s[n]!= \0 ) scanf( %s, st); ++n; printf( %d\n, strlen(st)); return (n); } char s[ ] { char *s main( ) { char *st; } int l; st = C Language ; l = strlen(st); printf( length=%d\n, l);

145 [ 5-4] strcpy 1) void strcpy(char s[ ], char t[ ]) { } int i = 0; while((s[i] = t[i])!= \0 ) i++; void strcpy(char *s, char *t) { } while((*s = *t)!= \0 ) { } s++; t++; void strcpy(char *s, char *t) { while(*s++ = *t++) ; }

146 5 2 3

147 1) static char days[7][10] = { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday }; [0] [1] [2] [3] [4] [5] [6] [7] [8] [9] days[0] S u n d a y \0 days[1] M o n d a y \0 days[2] T u e s d a y \0 days[3] W e d n e s d a y \0 days[4] T h u r s d a y \0 days[5] F r i d a y \0 days[6] S a t u r d a y \0

148 2 static char *days[7] = { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday }; Sunday\0 days[0] Monday\0 days[1] Tuesday\0 days[2] days[3] days[4] Wednesday\0 Thursday\0 days[5] days[6] Friday\0 Saturday\0 char *days[7]

149 #include <stdio.h> a= 0x194, a[0]= 0x194, &a[0][0]= 0x194 char a[4][5] = { abcd, efgh, ijkl, mnop }; a+1= 0x198, a[0]+1= 0x195, &a[0][1]= 0x195 main( ) **(a+1)= e, *(a[0]+1) = b { printf( a=%x, a[0]=%x, &a[0][0]=%x\n, a, a[0], &a[0][0]); printf( a+1=%x, a[0]+1=%x, &a[0][1]=%x\n, a+1, a[0]+1, &a[0][1]); printf( **(a+1)=%c, *(a[0]+1)=%c\n, **(a+1), *(a[0]+1)); } a[0] a[0]+1 a a b c d \0 a+1 e f g h \0 i j k l \0 m n o p \0 a, a[0], &a[0][0] a+1 a[0]+1

150 [ 5-5] 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]); }

151 C main int main( int argc, char *argv[ ]) int main( int argc, char **argv) -argc -argv argv[0] argv[1] argv[2] argv[argc-1] argc-1

152 [ 5-6] UNIX each each hello world hello world main( int argc, char *argv[ ]) { } int i; for(i=1; i<argc; i++) printf( %s%c, argv[i], (i< argc-1)? : \n ); main(int argc, char *argv[ ]) { } while(--argc > 0) argv printf((argc > 1)? %s : %s\n, *++argv); each hello world

153 * int (*fp)( ); int *fp( ) = C

154 [ 5-7] int leapyear( int year); main( ) { int (*fnptr)( ); fnptr = leapyear; result = (*fnptr)(2000); } /* leapyear(2000) */ int leapyear( int year) { if(((year % 4 = = 0) && (year % 100!= 0)) (year % 400) = = 0) return ( 1); else return ( 0); }

155 dispatch, index 0~9 index 0 fn0 1 fn1 int fn0( ), fn1( ), fn2( ), fn9( ); static int (*dispatch[ ])( ) = { fn0, fn1, fn2, fn9 }; (*dispatch[index])( );

156 [ 5-8] static char *p[2][3] = { }; abc, defg, hi, jklmnop, qrstuvwxyz, ABCD ***p p[0][0][0] a **p[1] p[1][0][0] j **(p[1]+2) p[1][2][0] A p[1][1][7] x (*(*(p+1)+1))[7] *(p[1][2]+2) p[1][2][2] C

157 [ 5-9] short *pi, *pj, t; long *pl; double *pd; *pd += (double) *pi; pi = &t; *pi = (short) *pl; pj = pi; *pj /= 3; ++pj; ++*pj; pi 1300 t 1350 pj 1380 pl pd

158 5 3 typedef typedef int LENGTH; typedef char *STRING; LENGTH len, maxlen; STRING lineptr[lines], alloc( ); int len, maxlen; char *lineptr[lines], *alloc( );

159 [ 5-10] int (*(*(*test( ))[ ])( )) [ ]; *test( ) typedef int AIN[ ]; *( )[ ] *( ) ( ) int ( ) [ ] typedef AIN *PAIN; typedef PAIN FPAIN( ); typedef FPAIN *PFPAIN; typedef PFPAIN APFPAIN[ ]; typedef APFPAIN *PAPFPAIN; test typedef PAPFPAIN FPAPFPAIN( ); FPAPFPAIN test; [ ]

160 [ 5-11] int (*(*test) ( ))[ ]; *test *( ) ( ) int ( )[ ]; test? typedef int AIN[ ]; typedef AIN *PAIN; typedef PAIN FPAIN( ); typedef FPAIN *PFPAIN; PFPAIN test;

161 [ 5-12] int (*test( ))[ ]; *test( ) int ( ) [ ]; test typedef int AIN[ ]; typedef AIN *PAIN; typedef PAIN FPAIN( ); FPAIN test;

162 typedef

163 C [ ] 1 2 identifier is 3 [x] an array of x ; function returning ; 4 * a pointer to ; 5 go to 3 6 type ;

164 int (*i) ( ); int ( * i ) ( ); i is a pointer to a function returning an int i is a pointer to a function returning an int

165 5 4 enum enum { } enum color { red, green, yellow, white, black }; /* */ enum color chair; enum color suite[10];

166 chair = red; suite[5] = yellow; if( chair = = green ) [ ] C 0 enum color { red, green, yellow = 5, white, black }; red=0, green=1, yellow=5, white=6, black=7 enum Boolean { FALSE, TRUE };

167 ---

168 6 1 struct

169 C Pascal record struct date { int day; int month; int year; int yearday; char mon_name[4]; } type end; date = record day: integer; month: integer; year: integer; yearday: integer; monname: array[0..3] of char; template struct date d1, d2; [ ] struct date struct

170 1 struct { } d; 2 struct date { } d; 3 typdef typedef struct { } DATE; DATE d, *pd, ad[10]; typedef

171 ANSI C static struct date d = { 27, 12, 1984, 361, Dec };

172 struct person { }; char name[namesz]; char address[adrsz]; char department[dpsz]; double salary; struct date birthdate; struct person table[100];

173 [ ] struct keyword { char *name; int count; struct keyword *next; } *base; base 5 int 2 float 4 char struct tnode { } *root; char *word; int count; struct tnode *left; struct tnode *right; root

174 2 struct person emp; emp emp.birthdate.year = 1970; emp.birthdate.month = 8; struct date *pd, d; pd struct date pd = &d pd = (struct date *) malloc(sizeof(struct date)); pd pd pd->year = 1958; strcpy(pd->mon_name, OCT ); pd->year (*pd).year C ->

175 struct { } *p; int x; int *y; ++p->x; x ++(p->x); (++p)->x; (p++)->x; p++->x; *p->y; *p->y++; (*p->y)++; *p++->y; p x x p y y y y p C ( ), [ ],, -> *, ++, --,

176 [ 6-1] #include <stdio.h> main( ) struct { int x; char *y; } *p, A[ ] = { }; 1, for, d d o p 3, for 2, while 3, p_while 4, switch 2, while, 3, do_while, 4, switch { } int i; p = A; printf( %d, ++p->x); printf( %d, ++(p->x)); printf( %d, (p++)->x); printf( %d, p++->x); printf( %c, *p->y); printf( %c, *p->y++); printf( %c, (*p->y)++); printf( %c, *p++->y); for(i=0; i<4; i++) printf( %d, %s\n, A[i].x, A[i].y);

177 6 2 [ 6-2] C

178 6-2 C struct Key { char *keyword; int keycount; } Keytab[ ] = { auto, 0, break, 0, case, 0, while, 0 }; #define MAXWORD 20 #define NKEYS (sizeof(keytab) / sizeof(struct Key)) #define LETTER a #define DIGIT 0 struct Key *binary(char *word, struct Key tab[ ], int n); char getword(char *w, int lim); char type( int c);

179 6-2 main( ) /* count C keyword */ { int t; char word[maxword]; struct Key *p; } while((t = getword(word, MAXWORD))!= EOF) if( t = = LETTER) if(( p = binary(word, Keytab, NKEYS))!= NULL) p->keycount++; for(p=keytab, p < Keytab+NKEYS; p++) if(p->keycount > 0) printf( %4d%s\n, p->keycount, p->keyword);

180 6-2 struct Key *binary(char *word, struct Key tab[ ], int n) { int cond; struct Key *low = &tab[0]; struct Key *high = &tab[n-1]; struct Key *mid; } while(low <= high){ mid = low + (high low) / 2; if((cond = strcmp(word, mid->keyword)) < 0) high = mid 1; else if ( cond > 0) low = mid + 1; else return (mid); } return (NULL);

181 6-2 char getword(char *w, int lim) { int c, t; } if(type(c = *w++ = getch( ))!= LETTER){ *w = \0 ; return ( c); } while(--lim > 0) { t = type(c = *w++ = getch( )); if( t!= LETTER && t!= DIGIT){ ungetch(c); break; } } *(w-1) = \0 ; return ( LETTER);

182 6-2 char type(int c) /* return type of ASCII character */ { if( c >= a && c <= z c >= A && c <= Z ) return ( LETTER ); else if ( c >= 0 && c <= 9 ) return ( DIGIT ); else return (c); }

183 6 3 struct keyword { char *name; int count; struct keyword *next; }; struct tnode { char *word; int count; struct tnode *left; struct tnode *right; };

184 struct link { int n; struct link *next; }; 1) struct link *first *p; p = first = (struct link *)malloc(sizeof(struct link)); p->next = NULL; for(i=0; i<= 10; i++){ p->n = i; p->next = (struct link *)malloc(sizeof(struct link)); p = p->next; } 1 NULL 2 NULL 3 NULL

185 2 p1->next = p->next; p->next = p1; p 1 NULL 2 NULL 3 NULL 3 q = p->next; p1 4 p->next = p->next->next; free(q); p q 1 NULL 2 NULL 3 NULL

186 [ 6-3]

187 [ 6-3] #include <stdio.h> #define MAXWORD 20 struct tnode { char *word; int count; struct tnode *left; struct tnode *right; }; struct tnode *tree(struct tnode *p, char *w); struct tnode *talloc( ); char *strsave(char *s); void treeprint(struct tnode *p);

188 [ 6-3] main( ) /* word frequency count */ { struct tnode *root; char word[maxword]; int t; root = NULL; while((t = getword(word, MAXWORD))!= EOF) if( t = = LETTER) root = tree(root, word); treeprint(root) }

189 [ 6-3] struct tnode *tree(struct tnode *p, char *w) / * install w at or below p */ { int cond; } if( p = = NULL ) { /* a new word has arrived */ p = talloc( ); /* make a new node */ p->word = strsave(w); p->count = 1; p->left = p->right = NULL; } else if((cond = strcmp(w, p->word)) = = 0) p->count ++; /* repeated word */ else if ( cond < 0 ) /* lower into left subtree */ p->left = tree(p->left, w); else /* greater into right subtree */ p->right = tree(p->right, w); return ( p );

190 [ 6-3] struct tnode *talloc( ) { return (( strcut tnode *)malloc(sizeof(struct tnode )); } char *strsave(char *s) { char *p; if((p = malloc(strlen(s)+1))!= NULL) strcpy(p, s); return ( p ); } void treeprint( struct tnode *p) / * print tree p recursirely */ { if(p!= NULL) { treeprint(p->left); printf( %4d%s\n, p->count, p->word); treeprint(p->right); } }

191 [ 6-3] C language book study pascal statement buy C book language buy study pascal statement

192 6 4 int 1 #define O-READ #define O-WRITE #define RW #define HIDE if( status & HIDE ) status = O-READ; 0x01 0x02 0x04 0x08 O_READ O_WRITE RW HIDE

193 2) struct FileStatus { unsigned O_READ:1; unsigned O_WRITE:1; unsigned RW:1; unsigned HIDE:1; }; struct FileStatus status; if(status.hide) status.o_read = 1;

194 struct instruction { unsigned opcode:8; unsigned opert1:4; unsigned opert2:4; }; struct instruction f; opcode opert1 opert

195 & 0

196 6 5 union union { }

197 [ ] union v_tag { int ival; float fval; char *pval; } uval; if(utype = = INT) printf( %d\n, uval.ival); else if (utype = = FLOAT) printf( %f\n, uval.fval); else if(utype = = STRING) printf( %s\n, uval.pval); else printf( bad type\n ); [ ]

198 [ ] struct { char *name; int flags; int utype; union { } uval; int ival; float fval; char *pval; } symtab[nsym]; symtab[i].uval.ival union Pascal

199 : strcu v_tag { int ival; float fval; char *pval; }; union v_tag { int ival; float fval; char *pval; } uval; struct v_tag union v_tag int float char * ival fval pval int ival float fval char* pval struct v_tag union v_tag

200 : union struct 0

201 / UNIX UNIX

202 7 1 / I/O C C I/O I/O UNIX

203 1. / / C / stdio.h #include <stdio.h> I/O int getchar(void) int putchar(int c) char *gets( char *s) int puts( char *s) c s s UNIX

204 [ ] #include <stdio.h> main( ) { } int c; while((c = getchar( ))!= EOF) putchar ( isupper(c)? tolower(c):c); 1 c int; 2 while((c = getchar( ))!= EOF) c=getchar( ) C getchar putchar isupper tolower UNIX

205 [ ] getchar( ) I/O / I/O [ 7-1] #include <stdio.h> main( ) { } int c; while((c = getchar ( ))!= EOF) putchar( c); isn't this <Enter> isn t this CTR+d UNIX

206 prog < infile prog > outfile otherprog prog otherprog prog prog otherprog cat file1 file2 lower > outfile otherprog prog UNIX

207 2 / 1) int scanf( 1 2 ) UNIX

208 scanf %[*][size][l][h]type type (type) d u o x e, f, g c s [ ] [^ ] % char letter[100]; scanf( %[a-z], letter); scanf( %[^,. ;], letter); /* */ /* */ UNIX

209 [ ] int i; float x; cahr name[50]; scanf( %2d %f %*d %2s, &i, &x, name); a72 * size l h type i = 56, x = 789.0, 0123, name = 45 a scanf -1 UNIX

210 2 int printf( 1 2 ) %[flags] [ width] [.prec] [l] type UNIX

211 (type) d u o x a~f X A~F f e e E E f f e f E c s \0 % UNIX

212 flags # 0 0x( 0X) %g %G width * prec e f g s * l type UNIX

213 [ ] int width = 10; printf( %*d, width, result); printf( :%*.*d:\n, 10, 6, 100); : : /* 10 result */ /* 10 6 */ [ ] hello, world 12 :%10s: :%-10s: :hello, world: :hello, world: :%20s: : hello, world: :%-20s: :hello, world : :%20.10s: : hello,wor: :%-20.10s: :hello, wor : :%.10s: :hello, wor: UNIX

214 3 sscanf(char * s, char *format [, pointer ]) s sprintf(char * s, char *format [, arg ]) s scanf printf sprintf main( ) { char buf[100], *cmd= pr -w, *file= /tmp/data ; int width = 80; sprintf(buf, %s %d %s, cmd, width, file); printf( %s\n, buf); } sscanf char *buf = ; float val1, val2; char oper; sscanf(buf, %f %c %f, &val1, &oper, &val2); UNIX

215 3 / #include <stdio.h> 1) fopen( ); 2) getc, putc, fgetc, fputc, fgets, fputs, fscanf, fprintf 3) fclose( ); UNIX

216 fopen FILE *fopen(const char *filename, const char *mode); fopen FILE fopen FILE *fp; FILE struct fopen fopen( ) FILE FILE UNIX

217 fopen fp = fopen( ) r w a r+ w+ a+ UNIX

218 w a fopen w a r NULL r+ w+ r+ a+ rb w+b [ ] UNIX

219 getc( fp ), putc(c, fp) fgetc(fp), fputc(c, fp) fscanf(fp, format, ), fprintf(fp, format, ) / FILE stdin, stdout, stderr getc, putc fgetc,fputc fgetc fputc getc putc stdio.h #define getchar ( ) getc(stdin) #define putchar(x) putc(x, stdout) UNIX

220 [ 7-2] cat x.c y.c z.c #include <stdio.h> void filecopy(file *fp); main( int argc, char *argv[ ]) { FILE *fp; if( argc = = 1) filecopy(stdin); else while(--argc > 0) if(( fp = fopen(*++argv, r )) = = NULL) { printf( cat: can t open %s\n, *argv); break; } } else { filecopy(fp); fclose(fp); } void filecopy( FILE *fp) { int c; while((c = getc(fp))!= EOF) putc(c, stdout); } UNIX

221 4 exit(1), exit(0) exit fclose _exit UNIX

222 [ ] cat main( int argc, char *argv[ ]) { FILE *fp; if( argc = = 1) filecopy(stdin); else while(--argc > 0) if(( fp = fopen(*++argv, r )) = = NULL) { printf( cat: fprintf(stderr, can t cat: open can t %s\n, open %s\n, *argv); *argv); break; exit(1); } else { filecopy(fp); fclose(fp); } } exit(0); UNIX

223 5 / char *fgets(char *s, int n, FILE *fp) fp n-1 s s NULL int fputs( char *s, FILE *fp) s \n fp EOF fgets s gets fputs fgets fgets gets fgets(buf, 81, stdin); UNIX

224 6 / size_t fread(void *ptr, size_t size, size_t nobj, FILE *fp) fp size nobj ptr size_t fwrite(const void *ptr, size_t size, size_t nobj, FLE *fp) ptr fp size nobj fread(buf, sizeof(struct Date), n, fp); fwrite(buf, sizeof(struct Date), n, fp); UNIX

225 7 2 #include <ctype.h> isalpha(c) c 0 0 isupper(c) islower(c) #define isupper(c ) (c >= A && c<= Z )?1:0 isdigit(c) isspace(c) toupper(c) tolower(c) c 0 0 c c UNIX

226 ungetc(c, fp) #include <stdio.h> c fp #include <stdlib.h> system(s) s system( date ); #include <stdlib.h> void *malloc(size_t size); void *calloc(size_t nobj, size_t n); void free(void *p); int *ip; ip = (int *) malloc(100*sizeof(int)); UNIX

227 #include <string.h> char *strcpy(char *s1, char *s2); char *strcat(char *s1, char *s2); int strcmp(char *s, char *t); int strlen(char *s); char st[20], *p= c language ; char *strchr(char *s, char c); char *strstr(char strcpy(st, *s1, char p); *s2); int feof(file *fp) 0 int fseek(file *fp, long offset, int origin) origin offset origin SEEK_SET SEEK_CUR SEEK_END fseek(fp, 0, SEEK_SET); long ftell(file *fp) fseek(fp, -5, SEEK_END); 5 UNIX

228 #include <stdlib.h> double atof(const char *s); int atoi(const char *s); long atol(const char *s); UNIX

229 7 3 UNIX / 1 UNIX / UNIX file descriptor [ ] UNIX

230 2 1) open creat 2) open fopen open 3) fopen creat fd = creat( char *name, int perms); name perms UNIX 9 bit rwx rwx rwx -1 UNIX

231 4) open #include <fcntl.h> (DOS io.h ) int fd; int open(char *name, int flags); fd = open(name, flags); name flags O_RDONLY O_WRONLY O_RDWR O_NDELAY O_APPEND O_TRUNC ( 0) 1 2 O_CREAT -1 UNIX

232 5) close(fd); 6) unlink(filename); UNIX

233 3. nr = read( ) nw = write( ) 1) read nr 0-1 2) write nw ) UNIX

234 [ ] #include <fcntl.h> #define BUFSIZE 512 main( ) { char buf[bufsize]; int n; } while((n = read(0, buf, BUFSZIE)) > 0) write(1, buf, n); UNIX

235 [ ] #include <fcntl.h> #define CMASK 0377 /* for making char s > 0 */ int getchar( ) { char c; /* char read */ } return(( read(0, &c, 1) > 0)? c & CMASK : EOF); UNIX

236 [ ] #include <fcntl.h> #define CMASK 0377 #define BUFSIZE 512 int getchar( ) { static char buf[bufsize]; static char *bufp = buf; static int n = 0; if( n = = 0){ n = read(0, buf, BUFSIZE); bufp = buf; } return ( (--n >= 0)? *bufp++ & CMASK : EOF); } UNIX

237 4. I/O [ ] pos n long lseek(int fd, long offset, int origin); int get(int fd, int pos, char *buf, int n) origin offset origin { SEEK_SET, lseek(fd, SEEK_CUR, pos, 0); SEEK_END offset long return(read(fd, buf, n)); lseek(fd, 0l, 2); } lseek(fd, -5l, 2); 5 lseek -1 UNIX

238 C 1983 ACM UNIX C Ken Thompson 1040 C C

239 char s[ ] = { \t, 0, \n, } ;, \n, \n, /, *, \n, (213 lines deleted) 0 }; /* The string is a * representations of the body * of this program from 0 * to the end */ main( ) { } int i; C printf( char \ts[ ] = { \n }; for(i=0; s[i]; i++) printf( \t%d\n,\n, s[i]; printf( %s, s); s C Trojan horse UNIX C Ken Thompson

240