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Transcription

1 C

2 ( CIP) C /. :, ISBN C C. TP312 CIP ( 2001 ) C * * : /16 : : : ISBN / TP311 :

3 C, C,,,, C,, ( ),, ( ), C C ++ JAVA, C,, C,,,,,,, 1, C, 2 C 3 5 C, C,,, 1

4 C 6 7, 8,, 9, 10, 11 C ASCII C, C,,,, C,,,,,, 1 11,,,,,, 87 ANSI C,,, MS-DOS Windows MS-DOS Turbo C, UNIX C,, : ( ), ( 2 4 ), ( 8 10 ), ( 11 ). ( ),,,,,,,,

5 1 C C C C C C C goto 55 1

6 C main C C C

7 typedef C A ASCII 209 B C 210 C C 210 D C 214 3

8 1 C, C C,, C, C C, 1. 1 C C 1969, ( Bell Laboratories) Ken Thompson D. M. Rithie UNIX 1970, Ken Thompson UNIX, BCPL ( ALGOL 60 CPL ) B 1973, D. M. RithieB C, K. Thompson D. M. Rithie C UNIX 1978, B. W. Kernighan D. M. Rithie The C Programming Language C, CC, C, ( ),, ( ), C 1987, ( ANSI) C 87 ANSI C, 1990, ISO 87 ANSI C ISO C C DOS MS C5. 0 Turbo C 2. 0, UNIX UNIX 4. 2BSD, C C ++ C, C ++ C, C ++ C, C C ++ Borland C ++ Visual C ++ JAVA C, C, 1

9 C C C : C,,, ( 10 % 20% ) C,,, C, C, C C, 34, C, C #, C,,, ( ),,, 1. 2 C C, C C 1. 1 #include stdio. h { printf( Good morning! \ n ) ; printf( * * * * * * * * * * * * * * * \ n ) ; : Good morning! * * * * * * * * * * * * * * *, #include stdio. h, stdio. h, C printf( ), C {, printf( ), 2

10 1 C \n, 1. 2 #include stdio. h / *, C * / { int r; / *, r ( int ) * / float area; / *, area ( float ) * / printf( Input r: ) ; / * r, * / scanf( % d, &r) ; / * scanf( ), r * / area = * r* r; / *, area * / printf( area = % f\ n, area) ; / *, area =, \n * / : Input r: 10 area = :,, / * * /,,, 1. 3 #include stdio. h / *, C * / { int a, b, c; / *, a, b, c int * / int max( int x, int y) ; / * int max, 2, int * / / * * / printf( Input a, b: ) ; / * a, b, * / scanf( % d, % d, &a, &b) ; / * 2 a b, * / c = max( a, b) ; / * max( ), c * / printf( max = % d \ n, c) ; / * c * / int max( int x, int y) / * max( ), int, x, y int * / { int z; / * int z * / if ( x > y) else z = y; z = x; return z; / * z * / : Input a, b: 16, 20 max = 20 2, main max, ( ) max, a, b 3

11 C max x, ymax z C, C : C, 1. 3, C : { ; ;,, C,, ; C, sum, mean, #include, #, ;, / * * /,,, C ( C ) 3 scanf( ) printf( ), 1. 3 max( ),, : ( ) { ; ;, ,,,,,, 4

12 1 C 1. 3,, ( 1 )?,,,,,,,,, , : 1, 100 ; 2,, : 1 ; 2 ; ; 3 ; ; 4 ; 100 ; ; 100, ;, 1 000,,,,,, 100, : sum,,, sum, sum = 0 c, mean,,, n,,, n, n = 0 5

13 C : sum0 ; n0; c; c sum, c + sumsum( ) ; n 1, n + 1n( ) ; n < 100, ( n < ,, n 100, 100, a, ) ; sum /n, mean, sum / nmean; mean,,, , n < 100 n < 1000 ( 2 ), , 1. 2 Y 1. 1 N sum= 0 n= 0 c sum= sum+ c n= n+ 1 n< 100 mean= sum n mean 1. 4 ( ),, ( ), ( ), 1. 2,,, ( ),, 1. 1 sum = 0 n = 0 0 sum sum0 = 0 0 sum sum ,, ch, :

14 1 C ch; ch ( \ n ), ; ch a ch z ch - ( a - A ) ch ch, ch ; ; ch ; ;,, ch 1. 3 : Y 1. 6 s = 3! + 5! + 7! + 9! s, n!, n = 3, 5, 7, 9 s = 0 ; n = 3; s = s + n! ; n = n + 2; n9,, ; s= 0 n= 3 fact( n) s= s+ n! n= n+ 2 n9 s N 1. 4 fact( x) i= 1 m= 1 ix Y m= m* i i= i+ 1 m 1. 6 N 1. 3 s; ch ch n Y Y ch ch ch N N 1. 5 n!? fact( x), x = n, fact ( n ) n! n!, fact( n) fact( x) ( m, i, i = 1, 2, 3,, x) : i = 1; m = 1 ; ix, ; m = m* i; i = i + 1 ; ; m 1. 4 ( 3 ) : 7

15 C,, ( ), 0 1 0, C C, 8 C 3 ( 1 ) 1. 4 C #include stdio. h / *, C * / { int c, n; / *, c, n ( int ) * / float sum, mean; / *, sum, mean ( float ) * / sum = 0; n = 0; / *, * / / * sum n * / do{ / * do{ while * / scanf( % d, &c) ; / * c* / sum = sum + c; / * * / n = n + 1; / * * / while( n < 100) ; / * * / mean = sum / n; / * * / printf( average = % f\ n, mean) ; /*, average =, \ n * / ( 2 ) 1. 5 C #include stdio. h / *, stdio. h, getchar( ) putchar( ) * / { char ch; / * ch ( char ) * / while ( ( ch = getchar( ) )! / * * / = \ n ) / * while, : ch * / { if ( ch >= a&& ch <= z ) / * if * / ch = ch - ( a - A ) ; / * ch, * / putchar( ch) ; / * * / printf( \ n ) ; / * * /

16 1 C : Good morning! GOOD MORNING!, while, {, { ( ), for, {, ( 3 ) 1. 6 C #include stdio. h /*, C * / { int n; /*, n int * / long s, fact( int) ; / * s long, long fact,, int * / for( s = 0, n = 3; n <= 9; n = n + 2) /* for, n = 3, 5, 7, 9, 4 * / s = s + fact( n) ; /* fact( x) * / printf( 3! + 5! + 7! + 9! = % ld \ n, s) ; /* s* / long fact( int x) / * fact( x), long, x int * / { long m = 1; / *, m i long int, m * / int i; / * * / for( i = 1; i < = x; i + + ) / * for, i = 1, 2, 3,, x, x * / m = m* i; / * i * / return m; / * m * / : 3! + 5! + 7! + 9! = long, s m fact int :,,, C, ; C, ; C if for while do-while,, C,,, 9

17 C 1. 4 C, C,,, C : A. ASCII C C,. c, test. c B.,, UNIX. o, MS-DOS. obj, CP / M. CRL,,,, C.,,,,, UNIX. out, MS-DOS. exe, CP/ M. com D.,,,,, C : * * * * * * * * * * * * * * * * * Welcome! * * * * * * * * * * * * * * * * * 1. 2,, 1. 3 s = ,, C 1. 4, :,,,, 64, :! C,? ( 1m ) 1. 5 e ! + 1 2! e ( n n! ),, C C

18 1 C 1. 7 C C C 11

19 2 ( Nikiklaus Wirth) : + =, : C, :, C : int char float double, void C, C, C 12

20 C C C 5 : char intfloat double void void 4 char: 1 1 ASCII int: 2 4 1, PC 2 float: 4 1 double: 8 1 void:,, void, 4, C : signed( ) unsigned( ) long( ) short( ) 4 signed unsigned short long char int, long double Turbo C ++ / bit char unsigned char signed char char int unsigned int unsigned signed int int signed unsigned short int unsigned short signed short int short long int long signed long int long unsigned long int unsigned long float e e + 38 double e e long double e e

21 C signed int,, int ( signed) ( signed) ( unsigned), : 0, ; 1,, short long int, 16 32, short int long int 16 32, long int , int int, int PC, int short int, 2 long C,,, C ( 1 ),, C 0 x, 0, : x = 0 xff; / * 255 * / y = 011; / * 9* /,, 2 : ( short int) ( int) ( long int) ( unsigned),, 2. 1, L U 123L, 4 123U int, 123LU long ( 2 ) C, : ( ), : ; e( E) 1 3, : e e e

22 2,, 4,,, ( bit), ( ), :,, z, 4, #, ( ) C ( ),, 2. 2, ASCII, 1 1, A ASCII 65, A \ 101 \ x41 A, ASCII, 65, 0x41, , 0 255,, A 65, A \0 NULL \ a BELL \ b BS \ f FF \ n NL( LF) \ r CR \ t HT ( TAB) \ v VT \ \ \ \ \ \ddd 1 3 \ xhh C, 15

23 C, This is a test,,,, ASCII C NULL( \0 ), n, n + 1, HELLO 5, 6, : H E L L O \0, a, a a, C,, ( ) C : const ( 1 ), : #define : #define PI PI ,,, #define C, ; PI ( ),, ; ,,,,, ( ), ( 2 ) const ( ) const, const,, : const = ; C, : const double pi = ; piconst ( ), const, 16

24 2 const :,, ;,, #define, const #define const ( ), #define, const,,, #define C ( 1 ) C : C,, C, count, Count, COUNT 3, ANSI ( Turbo C) 31,, 32, 33,, C 3 : 1 ) C : asm, auto, break, case, cdecl, char, const, continue, default, do, double, else, enum, extern, far, float, for, goto, huge, if, interrupt, int, long, near, pascal, register, return, short, signed, sizeof, static, struct, switch, typedef, union, unsigned, void, volatile, while int, int1 Int INT 2 ) C, ( printf) ( define) C,, 3 ) ( 2 ),,,, 17

25 C, : fmem: free memory available,,,,,,, ( ), 2. 3, selected char c cinchar disk drive; int i ireturnvalue, long l lnumrecs SelectedDiskDrive, string sz szinputstring int array ai aierrornumber,, char * psz pszinputstring, Microsoft Charles Simonyi 2. 3 Microsoft Windows,, Visual Basic Acess,,,,, Microsoft Windows,, C,,, : ;, C, ( ) : int x, y; / * int x, y * / float average; / * float average * / unsigned int z; / * unsigned int z * / double pi; / * double pi * / long m, n; / * long m, n * / 18

26 , : = ; : { int event = 5; char heat = C ; float time = 27. 5; : printf( The winning time in heat % c, heat) ; printf( of event % d was % f., event, time) ; The winning time in heat C of event 5 was 27. 5, C,, printf( ) : printf(, ) ;, : % d % o % x % u % c % s % f printf( ),,,, printf( ), 19

27 C, printf( ),,, : printf ( % s% d \ n, this is a string, 100) ; this is a string 100 printf ( this is a string % d \ n, 100) ; this is a string 100 printf ( % d is int, % f is float. \ n, 10, ) ; 10 is int, is float printf ( % s \ n, HELLO ) ; HELLO scanf( ) C, scanf( ) : scanf (, ) ;, : % d % o % x % c % s % f : & &a &x,, scanf( ), Tab scanf( ) { int a, b; printf( Enter integer a and b: ) ; scanf( % d% d, &a, &b) ; printf( a + b = % d \ n, a + b) ; printf( a - b = % d \ n, a - b) ; : Enter integer a and b: 6 3

28 2 a + b = 9 a - b = 3, scanf ( ) 2,, 2, a b, scanf ( ), : scanf ( % d, % d, &a, &b) ;,, : 6, 3,, & C + ( ) - ( ) * ( ) / ( ) % ( ), C, ++ ( ) - - ( ) ( ), C, /,, 10 / %,,% - 1,, 2. 2 #include < stdio. h > { int x, y; : printf( enter dividend and divisor: ) ; / * * / scanf( % d, % d, &x, &y) ; printf( quotient % d \ n, x / y) ; / * * / printf( remainder % d, x% y) ; / * * / enter dividend and divisor: 23, 5 quotient 4 remainder C, , 21

29 C, 1 1, ++ 1, : x ++ ; ++ x; x = x + 1; x - - ; - - x; x = x - 1; ++ x x + 1, x ++ x + 1 x, - - x x - 1, x - - x - 1 x x = 100, : x ++ x x ++ x - - x x - - x , 2. 3 { int a = 25, b = 80, aa, bb; a ++ ; b--; : aa = ++ a; bb = --b; printf( a = % d, b = % d, aa = % d, bb = % d \n, a, b, aa, bb) ; aa = a ++ ; bb = b--; printf( a = % d, b = % d, aa = % d, bb = % d \n, a, b, aa, bb) ; a = 27, b = 78, aa = 27, bb = 78 a = 28, b = 77, aa = 27, bb = 78, C, C,,, ,,,,,,,,,,, : c = ( ++ a% b-- + c) /d - 6* e : % + / * - =

30 C, C, : 0, 0,, 0, ; 0,,, C 2. 4 C :,, 0 ( ) 1 ( ) 2. 4 C > b > c b c >= b >= c b c == b == c b c <= b <= c b c < b < c b c! = b! = c b c, greater ch1 = A ; ch2 = B ; if ( ch2 > ch1) printf( great than ) ; than, ASCII, B A,, > >= < <= ==! =, x + 8 > y* 10, x + 8 y* 10, , : const float first = 0. 0; const float last = 70. 0; const float small = ; if( ( first + small* 10000) == last) ( first + small* 10000) == last, 1( ),, small ( first + small* ) last, 0( ) : if( abs( first + small* last) < 1e - 6) ( 10-6 ), 23

31 C 2. 7, 3 : ( &&) ( ) (! ),, 1,0 ( 2. 5 ) 2. 5 p q p && q pq! p : 10 > 5 &&! ( 10 < 9) 3 >= 4 C, :! ( ), &&( ), ( ) : a + b > cd &&! e :! + > &&! ( 10 < 9), 1, 10 > 5&&! ( 10 < 9), 1, 3 <= 4, 1( ), if, if #include < stdio. h > { int i; for ( i = 1; i <= 100; i ++ ) if (! ( i% 2) ) printf( % d, i) ; /* i, i% 2 0,! ( i% 2) 1 * / C, C, C : = 24 =, ( ) : a = c ++ ; / * * / b = x* y + 5; / * * /

32 2 e = a > b; / * * /,,, ;,, C : x = y = z = 2; x = ( y = ( z = 2) ) ; z = 2, 2 x, z = 2 2, y, y = z = 2 2, x, 2, : f = a = b + 3; / * f = ( a = b + 3) ; * /, C : if ( ( product = x* y) < 0) else printf( one number is negative \ n ) ; printf( positive product is: % d, product ) ; if, x* y product, 0, 1( ) 0( ) = a + = b a = a + b - = a - = b a = a - b * = a* = b a = a* b / = a / = b a = a / b % = a% = b a = a% b C, 2. 6,, , C

33 C 2. 7 ( ) ( ) int char 8, 8 0 char int int 8 char, int long int int float, double float double double double float float double 2. 9 : C, 3 1? 2: 3 (? ) ( : ) : 1, 0( ), 2 ; 0 ( ), 3 : x = ( a > b)? a: b; / * a b x * / y = ( x >= 0)? x: - x; / * x * / c = ( c >= a&& c <= z )? c - 32: c; / * c * / t? printf( % d, t) : printf( zero entered ) ; / * 0, printf( ), zero entered ;, * /,, : sgn = ( x > 0)? 1: ( x < 0? - 1: 0) /* x, 1, - 1, 0 0 * / , :,, int x = 3, y = 5; float z = 10. 0, a; a = x /y* z 26

34 2 a x / y x y, x / y , C : char short unsigned short long unsigned long float double long double,, 2. 7, ,, : char ch; int i; long l; float f; double d; : result= ( ch i ) + ( f * d ) - ( f + i ) ; int double double int double double double double double result float, float resultresult int, int result : ( ), C,, : ( int) x % n / * x int, * / ( int) sqrt( ( double) n) / * n double, sqrt int * /, ( int) x / y ( int) ( x /y), x, x / y,, : 27

35 C #include < stdio. h > { int i = 3; int j = 4; float f1 = i / j; float f2 = ( float) i / j; printf( 3 /4 = % f or % f depending on the type used. \ n, f1, f2) ; f1 i j,, 0 f2 i j, ( float) i float,, 0. 75,,, : #include < stdio. h > { int i; for( i = 1; i <= 100; ++ i) printf( % d /3 is : % f\ n, i, ( float) i /3) ; ( float),,,, void *, void, malloc ( ) student : struct student * p; p = ( struct student * ) malloc( sizeof( struct student) ) ; 2. 11, : 1, 2,, n, :, : x = ( y = 3, y + 1) ; 28

36 2, y 3, y + 1, 4, 4 ( y = 3, y + 1) x : printf( % d \n, ( 3 + 5, 15) ) ; / * 3 + 5, * / printf( % d, % d \ n, 3 + 5, 15) ; / * * /, C 9,,, : ( ) ( * / % ) ( + - ) ( ) ( < <= > >= ) (! = == ) ( & ) ( && ) (? : ) ( ), C,, 2. 8 C 1 ( ) [ ] - >. 2! * & sizeof 3 * / % < <= > >= 7! = == 8 & && 12 13?: 14 = + = - = * = / = % = & = =! = = = 15,, : a = b + c /d / fun( ) * 5,, : 29

37 C a = b + ( ( ( c / d) / fun( ) ) * 5),, C /*, * / ANSI C,, : / * this is / * an error * / * / Turbo C,, C,,,,,,, ;,, ( ),,,,,,,, C C C,, C, : int a = 3, x; x = a +++ a ++ ; :, a ++ 3, a 4, a ++ 4, a 5, x = 7, 6, a ++, a x = a a ++ ; y = x +++ x; y = a a; z = ++ a +++ a +++ a; x = a +++ a ++ ; : x = a ++ ; x = x + a ++ ; 30 int i = 3; printf( i = % d, i ++ = % d, ++ i = % d \ n, i, i ++, ++ i) ; :,, : i = 3, i ++ = 3, ++ i = 5, :

38 2 i = 5, i ++ = 4, ++ i = 4? PC,,,! C, : a&&b&&c a b c a 0, b c,, a b, a 0, b c,, a b,,,,, : ( a = 5 + 3) ++ b / * 1, a 8, b, 1 * / ( a = 5 + 3) && a > 0++ b / * 1, 1, b, 1 * / ( a = 5 + 3) && a < 0 && ++ b / * a < 0 0, 0, b, 1 * /, ( ),, ++ b, : ( a = 5 + 3) b, b 2. 1 : ( 1 ) x + y% 3* ( int) ( x + y) % 3 /7, x = 4. 2, y = 2. 5 ( 2 ) ( float) ( a + b) /5 + ( int) b% ( int) a, a = 3, b = 4 ( 3 ) a + = a, a - = 2, a* = 2 + 3, a = : ( 1 ) short a = e - 1; ( 2 ) double b = e2. 5 ; ( 3 ) long do = 0xfdaL; ( 4 ) float 2 and = 1 - e : ( 1) #include < stdio. h > { double d; float f; long l; int i; i = f = l = d = 20 / 3; printf( % d % ld % f % f\ n, i, l, f, d) ; ( 2) #include < stdio. h > { int i, j, m, n, s; i = 5; j = 10; m = ++ i; 31

39 C 32 n = j ++ ; s = m ++ - n; printf( i = % d \ tj = % d \ tm = % d \ tn = % d \ ts = % d \n, i, j, m, n, s) ; ( 3) #include < stdio. h > { char c1, c2; int i, j; c1 = a ; c2 = b ; printf( c1 = % c \t% d \ t% o\ t% x\ n, c1, c1, c1, c1) ; printf( c2 = % c \t% d \ t% o\ t% x\ n, c2, c2, c2, c2) ; ( 4) #include < stdio. h > { int x, y, z; x = y = z; z = 3; y = x ++- 1; printf( % d \t% d \ t, x, y) ; y = ++ x - 1; printf( % d \t% d \ n, x, y) ; y = z ; printf( % d \t% d \ t, z, y) ; y = - - z + 1; printf( % d \t% d \ n, z, y) ; 2. 4 ( 1) #include stdio. h ; { float r, s; printf( input the radius: \ n) ; scanf( % f, r) ; ( 2) #include stdio. h s = * r* r; printf( % f\ n, s) ; { int a, b, c, v; / * / * a, b, c are sides* /, / * v is volume of cube* /* / a = 2. 0; b = 3. 0; c = 4. 0 v = a* b* c; printf( % d \ n, v) ; 2. 5 :

40 2 C = 5 9 ( f - 32 ), : F 30, 60, 90, , 2. 8, a b, 2. 9, a, b, c,, 2. 10,, 3

41 3,,, C,, C 3. 1 C C C C 3 ( 1 ) C, : x = 0; /* * / i ++ ; /* * / printf( ) ; /* * /, ( 2 ), : 1 ), : : if else switch( ) : while while( ) 34

42 3 do do while( ) for for( ) 2 ), : continue switch break return goto ( 3 ),,,, ( 4 ) C, {,,, : if ( x < y) { int t; / * t * / t = x; / * t, x y * / x = y; y = t; x y,, :,,,, , 3, 1966, Bohm Jacopini 3, ,, ;,,,,, C, 3 C ; if switch; while, for do while 35

43 C 杂员 再 条件 晕 条件 晕 杂圆 杂员 杂圆 杂员 再 顺序结构选择结构循环结构 if ( 1 ) else if else if : if ( ) ;, else if 3. 2,,, if ;, if if,, : else if 3. 1,, #include < stdio. h > { int choice, value; printf (" Convert: \ n" ) ; / * * / printf (" 1: decimal to hexadecimal \ n " ) ; 36 0

44 3 printf( " 2: hexadecimal to decimal \ n " ) ; printf( " 3: decimal to octal \ n " ) ; printf( " 4: octal to decimal \ n" ) ; printf( " enter your choice: " ) ; scanf( " % d", &choice) ; / * * / if ( choice == 1) / * 1 * / { printf( " enter a decimal value: " ) ; scanf( " % d", &value) ; printf( " % d in hexadecimal is: % x\ n ", value, value) ; if ( choice == 2) / * 2 * / { printf( " enter a hexadecimal value: " ) ; scanf( " % x", &value) ; printf( " % x in decimal is: % d \ n ", value, value) ; if ( choice == 3) / * 3 * / { printf( " enter a decimal value: " ) ; scanf( " % d", &value) ; printf( " % d in octal is: % o\ n ", value, value) ; if ( choice == 4) / * 4 * / { printf( " enter a octal value: " ) ; scanf( " % o", &value) ; printf( " % o in decimal is: % d \ n ", value, value) ; : Convert: 1: decimal to hexadecimal 2: hexadecimal to decimal 3: decimal to octal 4: octal to decimal enter your choice: 3 enter a decimal value: 28 in octal is: 34 if,,, : if ( 2 ) else if else if, if : 37

45 C if ( ) 1; else 2; if 3. 3,,, if 1;, else, else 2 : if, else, if else, 3. 2, #include < stdio. h > { int x; printf( " enter a integer number: " ) ; / * * / scanf( " % d", &x) ; if ( x% 2 == 0) printf( " The number is even \ n " ) ; / * x 2, * / else printf( " The number is odd number \ n " ) ; / * x 2, * / , ( ) if #include < stdio. h > { int a, b; printf (" enter two number: " ) ; scanf (" % d% d", &a, &b) ; if( b) printf (" % f \ n", ( float) a /b) ; / * b 0, float * / else printf (" cannot divide by zero\ n" ) ; / * b 0, * /, if( b) if ( b! = 0) ( 3 ) if if if if, if if else if : if ( x) 38

46 3 if ( y) printf( " 1" ) ; else printf( " 2" ) ; if else? C : else else if,, else if ( y) else if( x), if : if ( x) { if ( y) printf( " 1" ) ; else printf( " 2" ) ; else if( x), if( y) if if_else_if, if_else_if, if,, if, if_else_if, if, 3. 4 #include < stdio. h > { int choice; int value; printf( " Convert: \ n" ) ; printf( " 1: decimal to hexadecimal \ n " ) ; printf( " 2: hexadecimal to decimal \ n " ) ; printf( " 3: decimal to octal \ n " ) ; printf( " 4: octal to decimal \ n" ) ; printf( " enter your choice: " ) ; scanf( " % d", &choice) ; if ( choice == 1) { printf( " enter decimal value: " ) ; scanf( " % d", &value) ; printf( " % d in hexadecimal is: % x\ n ", value, value) ; else if ( choice == 2) { printf( " enter hexadecimal value: " ) ; scanf( " % x", &value) ; printf( " % x in decimal is: % d \ n ", value, value) ; else if ( choice == 3) { printf( " enter decimal value: " ) ; scanf( " % d", &value) ; printf( " % d in octal is: % o\ n ", value, value) ; 39

47 C else if ( choice == 4) { printf( " enter octal value: " ) ; scanf( " % o", &value) ; printf( " % o in decimal is: % d \ n ", value, value) ; switch if_else_if,,, C, switch ( 1 ) switch switch : switch( ) { case 1: 1 case 2: 2 case n: default: n n + 1 switch, case,, case ; case,, switch, default n + 1 default, default,,,, 3 + 5, 4 * 8 switch n default n switch

48 3 switch : if : switch, if switch, case, switch, switch switch switch, switch if_else_if 3. 5 switch #include < stdio. h > { int choice; int value; printf( " Convert: \ n" ) ; /* * / printf( " 1: decimal to hexadecimal \ n " ) ; printf( " 2: hexadecimal to decimal \ n " ) ; printf( " 3: decimal to octal \ n " ) ; printf( " 4: octal to decimal \ n" ) ; printf( " enter your choice: " ) ; scanf( " % d", &choice) ; switch ( choice) { case 1: / * 1 * / printf( " enter decimal value: " ) ; scanf( " % d", &value) ; printf( " % d in hexadecimal is: % x\ n", value, value) ; break; case 2: / * 2 * / printf( " enter hexadecimal value: " ) ; scanf( " % x", &value) ; printf( " % x in decimal is: % d \ n", value, value) ; break; case 3: / * 3 * / printf( " enter decimal value: " ) ; scanf( " % d", &value) ; printf( " % d in octal is: % o \ n", value, value) ; break; case 4: / * 4 * / printf( " enter octal value: " ) ; scanf( " % o", &value) ; printf( " % o in decimal is: % d \ n", value, value) ; break; 41

49 C switch break, switch, switch ( 2 ) default switch default,, switch default : switch( ch) { case Y : case y : printf( " You answered YES! \ n" ) ; break; case N : case n : printf( " You answered NO! \n" ) ; break; switch,?,, default, : default: printf( " Unknown reponse: % d \n", ch) ;,, default default switch,, default, : default: printf( " invalid selection, try again \ n" ) ; ( 3 ) break 3. 5, break switch switch case,, break, switch switch, 1,..., n, n + 1 break, switch n default 2 n n break switch switch break, switch break, :,, break, break, break,, case break 42

50 3, switch, case, break : switch( country) { case China : case Japan : case India : printf( " Asia" ) ; break; case Britan : case France : case German : printf( " Europe" ) ; break; ( 4 ) switch switch switch, switch switch, switch case, : switch( x) { case 1: switch( y) { case 0: printf( " divide by zero error" ) ; break; case 2: break; case 1: process( x, y) ; break; 3. 6 ax 2 + bx + c = 0,, : b = 0 c = 0 a = 0 c0 b0 x = - c / b a0 d = b 2-4ac d0 d < 0 : #include < stdio. h > #include < math. h > 43

51 C { float a, b, c, d, x1, x2, real, imag; printf( " please input a, b, c = " ) ; / * 3 * / scanf( " % f, % f, % f", &a, &b, &c) ; if ( fabs( a) < = 1e - 6) / * a = 0 * / { if ( fabs( b) < = 1e - 6) printf( " error \ n" ) ; / * b = 0 * / else / * b0 * / printf( " The equation has a root: % 6. 2f \n", - c / b) ; else / * a0 * / { d = b* b - 4* a* c; if ( fabs( d) < = 1e - 6) / * d = 0 * / printf( " The equation has two equal roots: % 6. 2f \n", - b / ( 2* a) ) ; else if ( d > 1e - 6) / * d > 0 x1 x2 * / { x1 = ( - b + sqrt( d) ) / ( 2* a) ; x2 = ( - b - sqrt( d) ) / ( 2* a) ; printf( " distinct real roots: % 6. 2f and % 6. 2f \ n", x1, x2) ; else / * d < 0 * / { real = - b / ( 2* a) ; / * * / imag = sqrt( - d) / ( 2* a) ; / * * / printf (" The equation has complex roots: \n) ; / * a + bi * / printf (" % 6. 2f + % 6. 2fi \ n", real, imag) ; printf (" % 6. 2f - % 6. 2fi \ n", real, imag) ; if-else, if-else : ( ) 0, : if ( d == 0)... 0, 0 fabs ( d ) ( 1 e - 6),, d = y = : x ( 0x < 10) 5 x + 3 ( 10x < 20) 3 x - 11 ( 20x < 30) 2 x + 7 ( 30x < 40) 6 x ( x40 ),, 10 ( 0, 10, 20, 30), 10, : 44

52 3 x x / , switch #include < stdio. h > { int x, y, m; printf( " Please input x: " ) ; scanf( " % d", &x) ; if ( x > = 40) m = 4; else m = x /10; switch( m) { case 0: y = x; break; case 1: y = 5* x + 3; break; case 2: y = 3* x - 11; break; case 3: y = 2* x + 7; break; case 4: y = 6* x ; break; default: printf( " The input data is invalid. \ n" ) ; printf( " The result is % d \ n", y) ; 3. 3,,, C C for while do_while for :,, 50, 100,, for ( 1 ) for for : for( 1; 2; 3 ) ; 3,, for 1,, ; 2,, 2 45

53 C ; 3,,, 3 for #include < stdio. h > { int x; for( x = 1; x < = 100; x ++ ) printf( " % d ", x) ;, x 1x 100, printf( ) printf( ), x 1, x 1 00 x 1 0 0, for, x, x for x < = 100, x,, : #include < stdio. h > { int x; for( x = 100; x > 0; x - - ) printf( " % d", x) ;, for 0 99 : #include < stdio. h > { int i; for( i = 0; i < 100; i ++ ) { printf( " this is i: % d", i) ; printf( " and i square: % d \ n", i* i) ; for,, : x = 10; for ( y = 10; y! = x; ++ y) printf( " % d", y) ; printf( " % d", y) ;, x y,,, y 10,

54 3 ( 2 ) for for, 1 ) for,, x y : #include < stdio. h > { int x, y; for ( x = 0, y = 0; x + y < 100; ++ x, y ++ ) printf( " % d", x + y) ; 0 98, x y 1 2 ) for for, 2,, 3,, for 3,, 10: for ( x = 0; x! = 10; ) scanf( " % d", &x) ; 3 ) for, 3, : for ( ; ; ) printf( " this loop will run forever \ n" ) ;,, : for ( ; ; ) if ( scanf( " % d", &x) ) / *, * / printf( " if enter number then this loop will run forever \ n" ) ; else /*, scanf( ), 0, * / break; 4 ) for for, for : for ( t = 0; t < time; t ++ ) ; / * * /, time while ( 1 ) while while : while ( ) ; 47

55 C,,,, for, while,, while 3. 7,, A: wait( ) { char ch; ch = \0 ; / * ch * / while ( ch! = A ) ch = getchar( ) ; while, ch A, ch,,,, A, ch!, = A while, ch,, ch A while, while : while( ( ch = getchar( ) )! ( 2 ) while = A ) ; 3. 7 while, while, for, while?, while 3. 9 #include < stdio. h > { int count = 0; printf( " type in a phrase: \ n" ) ; while ( getchar( )! count ++ ; = \r ) / * * / printf( " \ ncharacter count is % d", count) ; : type in a phrase: cat character count is 3, while for?,,, 48 测试表达式 非园 循环体 憎澡蚤造藻语句的后继语句 0

56 3, while while : ( getchar( )! = \ r ) getchar( ),,,, \ r, \ r, while,, ( 3 ) while while, getchar( ), while ch getchar( ) : #include < stdio. h > { int count = - 1; char ch; printf( " type in a phrase: \ n" ) ; ch = getchar( ) ; while ( ch! = \ r ) { ch = getchar( ) ; count ++ ; printf( " \ ncharacter count is % d", count) ; while,?, ch ch, while, getchar( ) while, C while( 1 ) {,, : while( 1) { ch = getchar( ) ; printf( " \ nthe code for % c id % d. \ n", ch, ch) ;,, : if ( ) break; 非园 循环体 测试表达式 0 憎澡蚤造藻语句的后继语句 3. 8 do while 49

57 C do while ( 1 ) do while do{ ; while ( ) ;,, while do while do while 3. 8 do, do while do, ; while,, do while for while,,, ;, do while do while, 100 do{ scanf( " % d", &num) ; while( num > 100) ; ( 2 ) do_while do?,, do while while, while,, do while,, do while, do while : do{ printf( " convert: \ n" ) ; printf( " 1: decimal to hexadecimal \ n " ) ; printf( " 2: hexadecimal to decimal \ n " ) ; printf( " 3: decimal to octal \ n " ) ; printf( " 4: octal to decimal \ n" ) ; printf( " enter your choice: " ) ; scanf( " % d", &choice) ; while( choice < 1 choice > 4) ;,, 100 : { int count = 1; 50

58 3 int total = 0; do{ total + = count; count + = 2; while( count < 100) ; printf( " total = % d \ n", total) ; ( 1 ) while, a e : #include " stdio. h" #include " conio. h" / * clrscr( ) * / { char ch1, ch2; while ( ( ch1 = getchar( ) )! = EOF) / * ch1, ctrl + z * / { clrscr( ) ; / *, * / printf( " \ ntype in a letter from a to e : \ n" ) ; while ( ( ch2 = getchar( ) )! = ch1) / *, * / { printf( " \ nsorry, % c is incorrect. \ n", ch) ; / * * / printf( " \ ntry again. \ n" ) ; printf( " \ nthat s it! \ n" ) ; / *, * / while EOF( stdio. h ),, ;,,, ( 2 ) C,,, {,,, { Kernighan Ritchie, Allman, Whitesmiths 3 3 1) K&R C ( The C Programming Language), Brian Kernighan Dennis Ritchie, : while( ( c = getchar( ) )! = \ n ) { if ( ( c > = a &&c < = z ) ( c > = A &&c < = Z ) ) { c = c + 4; if ( c > Z &&c < = Z + 4 c > z ) c == c - 26; 51

59 C printf( " % c", c) ; K&R, {,, 2) Allman Allman : while( ( c = getchar( ) )! { = \ n ) if ( ( c > = a &&c < = z ) ( c > = A &&c < = Z ) ) { c = c + 4; if ( c > Z &&c < = Z + 4 c > z ) c == c - 26; printf( " % c", c) ; Allman, {, { 3) Whitesmiths Whitesmiths : while( ( c = getchar( ) )! { = \ n ) if ( ( c > = a &&c < = z ) ( c > = A &&c < = Z ) ) { c = c + 4; if ( c > Z &&c < = Z + 4 c > z ) c == c - 26; printf( " % c", c) ; Allman, Whitesmiths {,,, break continue ( 1 ) break break : break; break switch switch break switch, break,, s = n n

60 3 #include < stdio. h > { int i = 1, s = 0; while( 1) { s + = i* i; if ( s > 1000) / * s, s > 1000 * / break; printf( " n = % d \ n", i - 1) ;,, break ( 2 ) continue continue : continue; continue,, continue , 7 #include < stdio. h > { int s; for( s = 1; s < = 1000; s ++ ) if ( s% 3 == 0) / * 3 * / if( s% 7 == 0) / * 7 * / continue; / *, * / else /* 3, 7 * / printf( " % d ", s) ; continue break continue, break , { int num, c; printf( " input an integer: " ) ; / * * / scanf( " % d", &num) ; 0 测试表达式非园 continue 憎澡蚤造藻语句的后继语句 continue do { c = num% 10; / * 10,, num * / printf( " % d", c) ; / * * / 53

61 C while( ( num / = 10) > 0) ; / * num, 10 * / printf( " \ n" ) ; { int m, n, flag; /* flag, 1, 0 * / printf( " % d ", 2) ; /* 2 * / for( m = 3; m < = 1000; m ++ ) /* m * / { flag = 1; /* flag 1, m * / for( n = 2; n < m; n ++ ) /* n, 2 m - 1 * / if( m% n == 0) /* n m, * / { flag = 0; break; if( flag == 1) printf( " % d", m) ; / *, * / m, m : break n m, flag : ;, n, n sqrt( m) m - 1,, #include " math. h" / * sqrt( ) * / { int m, n, flag; /* flag, 1, 0 * / printf( " % d", 2) ; /* 2 * / for( m = 3; m < = 1000; m + = 2) /* m * / { flag = 1; /* flag 1, m * / for( n = 2; n < sqrt( m) ; n ++ ) / * n, 2 sqrt( m) * / if( m% n == 0) /* n m, * / { flag = 0; break; if( flag == 1) printf( " % d", m) ; / *, * / 3. 4 goto goto goto C,, goto, 1 100, goto : 54

62 3 x = 1; loop1: x ++ ; if ( x < 100) goto loop1; goto : for(... ) { for(... ) { while(... ) { if(... ) goto stop; stop: printf( " error in program. \ n) ; break,,, goto, goto goto,,, goto, goto,, goto , 81, 9 :, : 144( 12* 12) 676( 26* 26), #include < stdio. h > { int n, k, a, b, c; for ( k = 1; ; k ++ ) / * * / { n = k* k; if ( n < 100) continue; / * n, * / if ( n > 999) break; / * n, * / a = n / 100; / * a * / b = ( n - a* 100) /10; / * b * / c = n% 10; / * c * / if (! ( a - b) * ( a - c) * ( b - c) ) / * * / printf( " n = % d = % d* % d \ n", n, k, k) ; 55

63 C s = 1 - #include < stdio. h > { float s = 0. 0, w, f = ; int i; printf( " please input n: " ) ; scanf( " % d", &n) ; for ( i = 0; i < = n; i ++ ) { n - 1 f = ( ) * f; / * f * / w = f / ( 2* i + 1) ; / * w * / s + = w; printf( " the result is % d. ", s) ; : x sin( x) = 0 x0 = 1, 10-6 x n + 1 = x n - f( x n ) f ( x n ), x n + 1 f( x) = 0 f( x) = x sin( x), f ( x) = sin( x) + xcos( x) #include < stdio. h > #include < math. h > { float x1, x0 = 1, f, f1; do{ x1 = x0; /* * / f = x0* sin( x0) ; / * f( x) * / f1 = sin( x0) + x0* cos( x0) ; / * f ( x) * / x1 = x0 - f/ f1; / * * / while( fabs( x1 - x0) > 1e - 6) / * * / printf( " The result is % f6. 2. ", x1) ; 3. 1, 3. 2, 3. 3, 3. 4 : 56

64 , 3 2, 5 3, 7 2,? 3. 6 e = 1 1! + 1 2! n!, ,,, n, 57

65 4 C, C,, ( 1 ), : [ ] ;,, ;,, s name : int s[ 10] ; char name[ 50] ; ( 2 ),,?, : [ ], s[ 5] name[ 33] C, 0, s 9, 10, s[ 0 ] s [ 1 ] s [ 2 ]... s[ 9 ] name 49, 50, name[ 0 ] name[ 49] 58

66 4 :, ( 3 ), C,, s, s 4. 1 s[ 0] s[ 1] s[ 2] s[ 3] s[ 4] s[ 5] s[ 6] s[ 7] s[ 8] s[ 9] 4. 1 s ( 1 ) C,, : [ ] = { ;,,,,, : int s[ 10] = {0, 2, 4, 6, 8, 9, 7, 5, 3, 1 ; 4. 1, #include < stdio. h > #define LIM 5 int table[ LIM] = {50, 20, 10, 5, 1 ; /* table * / { int dex, amount, quantity; printf( " : " ) ; scanf( " % d", &amount) ; for ( dex = 0; dex < LIM; dex ++ ) { quantity = amount /table[ dex] ; printf( " = % 2d, ", table[ dex] ) ; printf( " = % 2d \ n", quantity) ; amount = amount% table[ dex] ; : : 138 = 50, = 2 = 20, = 1 = 10, = 1 = 5, = 1 = 1, = 3 59

67 C , 1, 1, 1 3 : 50 ( amount ), 50 ( ) ;, ( % ) amount, 20 5,, : int table[ LIM] = { 50, 20, 10, 5, 1 ; {,, table [ 0 ] 50, table[ 1 ] 20,, table[ 4] 1 ( 2 ) LIM ( #define 5) : int table[ LIM] = {50, 20, 10, 5, 1 ;,,?, 0 ; : int s[ 10] = {0, 2, 4, 6, 8; s[ 5] s[ 9] 0 : int table[ ] = {50, 20, 10, 5, 1; table? :,,,,, #include < stdio. h > #define N 20 / * 20 * / { int i, max, min, s[ N] ; for( i = 0; i < N; i ++ ) scanf( " % d", &s[ i] ) ; / * s * / max = min = s[ 0] ; / * 1 * / for( i = 1; i < N - 1; i ++ ) / *, * / if ( s[ i] > max) max = s[ i] ; else if ( s[ i] < min) min = s[ i] ; printf( " max = % d, min = % d \ n", max, min) ;

68 fabonacci 20 1, 2 : 1, 1, fabonacci : 1, 1, 2, 3, 5, 8, 13, 21, { int i; int f[ 20] = {1, 1 ; /* f, 1 * / for ( i = 2; i < 20; i ++ ) / * 3, * / f[ i] = f[ i - 1] + f[ i - 2] ; for ( i = 0; i < 20; i ++ ) / * * / { if( i% 5) printf( " \ n" ) ; / * 5 * / printf( " % 12d", f[ i] ) ;,, for, 1 1, ( 1 ) C,, \0 ( 0), 1, 10, : char str[ 11] ;,, \0, ( 2 ) 1 ),, : char s1[ 10] = { H, e, l, l, o, \0 ;, s

69 C S H e 1 1 o \0 \ 0 \0 \0 \0 : 2 ) 4. 2 s1 C,, char s1[ 6] = " Hello" ;, \ 0,,, : char s2[ ] = " This is a string" ; s ,?, scanf( ), : { char name[ 15] ; printf( " Enter your name: " ) ; scanf( " % s", name) ; printf( " Greetings, % s. \ n", name) ; : Enter your name: Mary Greetings, Mary. scanf( ) name \0 : for ( i = 0; i < 5; i ++ ) scanf( " % c", &name[ i] ) ; : name[ 0] = M ; name[ 1] = a ; name[ 2] = r ; name[ 3] = y ; name[ 4] = \ 0 ;, : name = Mary ;, name,, : char name[ 15] = Mary, name1[ 15] ; name1 = name; C,

70 4 ( 1 ) gets( ) gets( ) : gets( ) ;, gets( ),, gets( ) stdio. h, #include < stdio. h > { char str[ 80] ; printf( " enter a string: " ) ; gets( str) ; printf( " % s \ n", str) ; str printf( ), : gets( ),,, gets( ), ( 2 ) C : strcpy ( ) strcat( ) strlen( ) strcmp ( ), : string. h 1 ) strcpy( ) strcpy( ) : strcpy( to, from) strcpy( ) from to to from, hellostr : #include < stdio. h > #include < string. h > { char str[ 80] ; strcpy( str, " hello" ) ; printf( " % s", str) ; 2 ) strcat( ) strcat( ) : 63

71 C strcat( s1, s2) ; strcat( ) s2 s1, s2, hello there : #include < stdio. h > #include < string. h > { char s1[ 20], s2[ 10] ; strcpy( s1, " hello" ) ; strcpy( s2, " there" ) ; strcat( s1, s2) ; printf( " % s", s1) ;, s1, s1 s2, 3 ) strlen( ) strlen( ) : strlen( s) ; s strlen( s) s : #include < stdio. h > #include < string. h > { char str[ 80] ; printf( " enter a string: " ) ; gets( str) ; printf( " % d", strlen( str) ) ;, hi, there, 8 strlen( ) 4 ) strcmp( ) strcmp( ) : strcmp( s1, s2) ; strcmp( ), 0, s1 s2, ; s1 s2, flag , { char s[ 80], password[ ] = A123 ; / * password * / int flag = 0, n = 3; / * flag, 0, n * / do{ printf( " enter password: " ) ;

72 4 gets( s) ; / * * / if (! ( strcmp( s, password) ) / * * / { printf( " OK! \ n" ) ; flag = 1; / * flag 1 * / break; / * * / else if( n > 0) / * * / { printf( " password error, input again! \ n" ) ; while( n > 0) ; if(! flag) n - - ; / * * / { printf( " sorry, you is nt valid user, goodbye! \ n" ) , binary, #include < stdio. h > #include < math. h > #define M 16 { char ch, binary[ M] ; int i, j, dec, ndec, index = 0; / * index binary * / printf( " : " ) ; scanf( " % d", &dec) ; ndec = abs( dec) ; / * dec * / while( dec) { str[ index ++ ] = dec% ; / * * / dec / = 2; binary[ index - - ] = \0 ; / *, index \0 * / for ( i = 0, j = index; i < j; i ++, j - - ) /* * / { ch = binary[ i] ; binary[ i] = binary[ j] ; binary[ j] = ch; printf( " % d : % s \ n", dec, str) ; : : , ( ) 65

73 C #include < stdio. h > main ( ) { int c, i, nwhite, nother, ndigit[ 10] ; / * : nwhite, ndigit[ 10] ndigit[ 0] ndigit[ 9] 0 9, nother* / nwhite = nother = 0; / * 0 * / for ( i = 0; i < 10; ++ i) ndigit[ i] = 0; while( ( c = getchar( ) )! { switch( c) = EOF) { 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: printf( " digits = " ) ; ++ nother; / * * / break for ( i = 0; i < 10; ++ i) printf( " % d", ndigit[ i] ) ; printf( ", white space = % d, other = % d \n", nwhite, nother) ;, int ndigit[ 10] 10 ndigit : if ( c > = 0&& c < = 9 ) c, : c - ndigit 0, 4. 3 C,, :

74 4 [ 1] [ 2] ; [ 1] [ 2] = { ;, 1, 2, a 34( 3 4 ) int : int a[ 3] [ 4] ; 0, a 2, 3,,, ( a ) : a[ 0 ] [ 0 ] a [ 0 ] [ 1 ] a [ 0 ] [ 2 ] a [ 0 ] [ 3 ] a [ 1 ] [ 0 ] a [ 1 ] [ 1 ] a [ 1 ] [ 2 ] a[ 1 ] [ 3 ] a[ 2] [ 0] a[ 2] [ 1] a[ 2] [ 2] a[ 2] [ 3 ], ( ) ( ) a [ 3 ] [ 4] 3 a[ 0] a [ 1 ] a [ 2 ], a [ 0] a[ 1] a[ 2 ] 3 a[ 0 ] 4, a[ 0] [ 0] a[ 0] [ 1 ] a[ 0] [ 2] a[ 0] [ 3] a[ 1] 4, a[ 1] [ 0] a[ 1] [ 1 ] a[ 1] [ 2] a[ 1] [ 3], a[ 2] 4, a[ 2 ] [ 0 ] a[ 2 ] [ 1 ] a[ 2] [ 2] a[ 2] [ 3], : int a[ 3] [ 4] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ; : : int a[ ] [ 4] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ; 2 : int a[ 3] [ 4] = { {1, 2, 3, 4, {5, 6, 7, 8, {9, 10, 11, 12 ; int a[ ] [ 4] = { {1, 2, 3, 4, {5, 6, 7, 8, {9, 10, 11, 12 ;, : int a[ ] [ 4] = {{1, 2, {, {0, 10, 11, 12 ; : : 67

75 C [ 1] [ 2] 1, #include < stdio. h > #define M 5 #define N 4 { int i, j, data[ M] [ N] ; for ( i = 0; i < M; i ++ ) / *, i, j * / for ( j = 0; j < N; j ++ ) scanf( " % d", &data[ i] [ j] ) ; for ( i = 0; i < M; i ++ ) / *, i, j * / { for ( j = 0; j < N; j ++ ) printf( " % 8d", &data[ i] [ j] ) ; printf( " \ n" ) ; / * * /,,,, : a[ 1] [ 2] = 3; a[ 2] [ 3] = a[ 1] [ 2] + 5; , : , 61 { 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 ; / * * / int year, month, day; int i, leap, dayth; /* dayth * / printf( " - - : " ) ; scanf( " % d - % d - % d", &year, &month, &day) ; leap = year% 4 == 0 && year% 100! = 0 year% 400 == 0; / * leap * / dayth = day; for( i = 1; i < month; i ++ ) dayth + = daytab[ leap] [ i] ; printf( " % d % d % d % d ", year, month, day, dayth) ;? daytab

76 4 leap : leap = year% 4 == 0&&year% 100! = 0 year% 400 == 0; 4 100, 400, 1900, 2000 leap 0( ) 1( ), daytab :? 4. 4 C : [ 1] [ 2] [ N] ; [ 1] [ 2] [ N] = { ;, t 223 float : float t[ 2] [ 2] [ 3] ;, 3, 2, 1, : t[ 0] [ 0] [ 0] t[ 0] [ 0] [ 1] t[ 0] [ 0] [ 2] t[ 0] [ 1] [ 0] t[ 0] [ 1] [ 1] t[ 0] [ 1] [ 2] t[ 1] [ 0] [ 0] t[ 1] [ 0] [ 1] t[ 1] [ 0] [ 2] t[ 1] [ 1] [ 0] t[ 1] [ 1] [ 1] t[ 1] [ 1] [ 2], t[ 2] [ 2] [ 3] 22 t[ 0] [ 0] t[ 0] [ 1] t[ 1] [ 0] t[ 1 ] [ 1], 3 2 t[ 0] t[ 1], 2 3,,,, : = 2 160, 4 320, ( 8 ), , 4. 5 C,,,, N, N,, C,, (,! ) { int crash[ 10] ; for ( i = 0; i < 100; i ++ ) crash[ i] = i; 69

77 C, crash 10, 20, 100, 200,,, C?, C, ,,, :, ( ),, ;,,, N N - 1, #include < stdio. h > #define N 20 / * 20 * / { int i, j; int s[ N], t; for( i = 0; i < N; i ++ ) scanf( " % d", &s[ i] ) ; / * s * / for( i = 0; i < N - 1; i ++ ) / *, N - 1 * / for( j = 0; j < N - i - 1; j ++ ) / * * / if ( s[ j] > s[ j + 1] ) / *, * / { t = s[ j] ; s[ j] = s[ j + 1] ; s[ j + 1] = t; for( i = 0; i < N; i ++ ) / * * / printf( " % 10d", s[ i] ) ; ,, 505 mark 50, 50 average 50 : #include < stdio. h > #define M 50 #define N 5 { int mark[ M, N], i, j; float average[ N], t; printf( " : \ n" ) ; printf( " \n" ) ; for( i = 0; i < M; i ++ ) 70

78 4 for( j = 0; j < N; j ++ ) scanf( " % d", &mark[ i] [ j] ) ; for( i = 0; i < M; i ++ ) /* * / { t = 0; /* t * / for( j = 0; j < N; j ++ ) t + = mark[ i] [ j] ; average[ i] = t / N; printf( " \ n" ) ; printf( " " ) ; printf( " " ) ; for( i = 0; i < M; i ++ ) /* * / { for( j = 0; j < N; j ++ ) printf( " % 6d", mark[ i] [ j] ) ; printf( " % 12. 1f\ n", average[ i] ) ; printf( " " ) ; : : : 2, 2 2,, 3 3 3, 5,, 50 :, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,, 97, 98, 99, 100,, 5, 7, 9, 11,, 97, 99,,, 7, 11,, 97 #include < stdio. h > #define M

79 C { int i, p, flag, new, s[ M] ; for( i = 2; i < = M; i ++ ) s[ i] = i; / * s * / p = 0; do{ flag = 0; / * flag, 1 * / while (! flag) / * * / { if ( s[ p]! = - 1) / *,, * / { new = s[ p] ; flag = 1; else p ++ ; / * s[ p] - 1,, * / for( i = p + 1; i < = M; i ++ ) / * new * / if ( ( s[ i]! = - 1) &&( s[ i] % new == 0) ) s[ i] = - 1; while( new < = M/2) ; for( i = 2; i < = M; i ++ ) /* * / if ( s[ i]! = - 1) printf( " % 4d", s[ i] ) ; ( 1) #include < stdio. h > { int a[ 10], i, k = 0; for( i = 0; i < 10; i ++ ) a[ i] = i; for( i = 0; i < 10; i ++ ) k + = a[ i] + i; printf( " % d \ n", k) ; ( 2) #include < stdio. h > { int i, j, row, col, m; int a[ 3] [ 3] == {{1, - 2, 3, {27, 36, 45, { - 56, 47, 89 ; m = a[ 0] [ 0] ; for( i = 0; i < 3; i ++ ) for( j = 0; j < 3; j ++ ) if ( a[ i] [ j] < m) { m = a[ i] [ j] ; row = i; col = j;

80 4 printf( " % d, % d, % d \ n", m, row, col) ; 4. 2, : AZ BY CX az by cx 1 26, i ( 26 - i + 1), 4. 3, s2 s1 strcpy, \0, \0 : 4. 4,, space space paces acesp cespa espac 4. 5, string position, character abcdefgh 5 D, abcddefgh 4. 6 strcmp,,, ASCII : abcdefg abceef, , 4. 8, 4. 9 A + B AB a, 3

81 5 C C,,, C,, C ( 1 ),,,,,, short a , a 2010 a, a a, 5. 1 C,,, pa, a, pa = &a; &, &a a a &a: 2010 a, a, a ; pa, a, apa a a 74

82 5 pa pa = &a a, pa a, a pa pa * pa, *,, 5. 2,, a 2010, a 2010,, pa s a pa ( 2 ) & * 5. 2 & *, &, : &, &a &b[ 2] *, : * pa, &( * px) px, px * ( &x) x, x, & * &a a * pa pa a 5. 3 y = x px = &x; y = * px y = x; px = &x; y = * px; 5. 4 pa = &a * pa = a, x y,,, 5. 3 px = &z, y = * px, y z x pa = &a * pa = a, pa a, a pa, * pa a; pa a, a * pa, ( 5. 5) : px, * pxpx, &pxpx &px 5. 5 px * px px * px &px 75

83 C ( 3 ),,,, ,,, ( 1 ) : * ; : int * pc; / * pc int * / float * pa; / * pa float * / char * name; / * name char * /, : int * pc, * pd, a1, a2; float * pa, d; char * name, * addr, str[ 80] ;, C *, * *,,,,,,,, C, int pc char name, int char ( 2 ), : : : * = ; int * pa = &a, * px = &x; / * pa px, int a x * / float * s = &ss; / * s, float ss * /,, : 76 int n; int * p = &n; :

84 5 int n, * p = &n;, : float x, * p = &x, * q = p;, q p, x, : int * p = 0; int * p = NULL; NULL 0 stdio. h NULL : #define NULL ,,, : &, : int a, * pa; pa = &a; / * pa a * /, : char c, * s1 = &c, * s2; s2 = s1; / * s1 s2 c * /, : char * str, ch[ 80] ; str = ch; / * str ch, str ch * /,, int * p1, * p2, a[ 20] ; p1 = a; p2 = p1 + 5; p1 = p2-3; p1 + = 2; p2 - = 10; int * c, a = 20, * b = &a; float * p; : b = 2000; / * * / p = b; / * * / c = * b; c = a; / * * / 5. 1 a b, #include " stdio. h" 77

85 C {int a, b, * t, * a1 = &a, * a2 = &b; / * a1 a2, a1 a, a2 b * / scanf( " % d, % d", &a, &b) ; if ( a > b) / * a > b a1, a2 * / { t = a1; a1 = a2; a2 = t; / * a1 a2, a1 b, a2 a * / printf( " a = % d, b = % d \ n", a, b) ; printf( " min = % d, max = % d \ n", * a1, * a2) ; : 6, 3 a = 6, b = 3 min = 3, max = , a b, a1 a2, a1, a2,, 5. 6,,,, p : int * p, a = 5; /* p, p, p * / * p = a; /* p, * / pa pb ( ), n, : pa + n, pa - n, pa + +, + + pa, pa - -, - - pa, pa - pb ( 1 ) n, n,, pa short, px long, pa = pa + 1, pa 2; px = px + 1, px 4, p, p n : p ( n ) 78

86 5, p n, C,,, 5. 7, pa a pa a[ i], pa n a[ i] n, * ( pa n) ( 2 ) (! ) pa - 4 pa - 3 pa - 2 pa - 1 pa pa + 1 pa + 2 pa + 3 pa + 4 a[ i - 4] a[ i - 3] a[ i - 2] a[ i - 1] a[ i] a[ i + 1] a[ i + 2] a[ i + 3] a[ i + 4] * ( pa - 4) * ( pa - 3) * ( pa - 2) * ( pa - 1) * pa * ( pa + 1) * ( pa + 2) * ( pa + 3) * ( pa + 4) 5. 7 pa n a,,, int pa, pa n int a a : pa = a; / * pa a * / for( i = 0; i < n; i + + ) { printf( " a[ % d] = % d \ n", i, * pa) ; / * pa * / pa + + ; / * pa * /,, 4 ( y pa ) y = * pa + + ;,, : y = * ( pa + + ), pa, y, pa y = * + + pa; y = * ( + + pa),, pa, pa ( ), y y = ( * pa) + + ;, pa, y, pa y = + + * pa; y = + + ( * pa),, pa,,, y 79

87 C 5. 2 #include " stdio. h" s r {char s[ ] = " Good morning! " char r[ 20], * st, * rt; st = s; rt = r; / * st rt s r * / while ( ( * rt + + = * st + + )! printf( " s string is % s \ n", s) ; printf( " r string is % s\ n", r) ; : s string is Good morning! r string is Good morning! = \0 ) ;, ( * rt + + = * st + + )! = \0 : st rt, \0 st rt,,, st rt s r,, st rt,, \0, while ( ( * rt + + = * st + + )! = \0 ) ; while ( * rt + + = * st + + ) ;, : ( * rt = * st)!? ( 3 ) C,,,,, 5. 8, p q a p q a[ 2 ] a[ 9 ], q - p 7, p - q #include " stdio. h" {char str[ 30], * s; s = str; / * s str * / printf( " Enter a string( less than 30 characters) : \ n" ) ; scanf( " % s", str) ; / * * / while ( * s! = \ 0 ) s + + ; / * s * / printf( " The string length is % d \n", s - str) ; : Enter a string( less than 30 characters) : p q 5. 8 = \0, a[ 2] a[ 3] a[ 4] a[ 5] a[ 6] a[ 7] a[ 8] a[ 9] a

88 5 WINDOWS2000 The string length is 11, s \0 : while ( * s + +! = \0 ) ; while ( * s + + ) ;,,, s?,? , p q, p > q, p q ( ), p = = q 1, p q, p < q, p q p, p = = 0 p! = 0, p = = NULL p! = NULL 5. 3,,, ( 1 ), int a pa, : int a[ 20], * pa; : pa = a; pa = &a[ 0] ; a, a[ 0], pa * pa a[ 0] : int a[ 20], * pa = a;, a[ 5] : pa = &a[ 5] ; * pa a[ 5] ( 2 ),, 3 : 81

89 C, a[ i],, C, a + i a i a[ i], * ( a + i) a[ i], A. pa = a, pa + i pa i a[ i], * ( pa + i) a[ i] B. pa = a, * ( pa + i) a[ i], C pa[ i] pa i, pa a, pa = a ( pa a ), a[ i] : 5. 4 a[ i] * ( a + i) * ( pa + i) pa[ i] #include " stdio. h" {int * p, num[ 4], i; p = num; / * * / for ( i = 0; i < 4; i + + ) * ( p + i) = i + 1; / * * / for ( i = 0; i < 4; i + + ) printf( " num[ % d] = % d \ t", i, num[ i] ) ; / * * / printf( " \ n" ) ; : 82 num[ 0] = 1 num[ 1] = 2 num[ 2] = 3 num[ 3] = #include " stdio. h" 10, data, 10 {float * p, * pend, data[ 10], max, min; * p = * pend = data; / * * / printf( " Enter 10 number: \ n" ) ; for ( i = 0; i < 10; i + + ) scanf(% f, pend ++ ) ; / * pend + +, * / / *, pend data[ 9] * / max = min = * data; / * data[ 0] * / for ( p = data + 1; p < pend; p + + ) / *, p data[ 1] data[ 9] * / if ( * p > max) max = * p; else if ( * p < min) min = * p; printf( " max = % f\ tmin = % f\ n", max, min) ;

90 5 : Enter 10 number: max = min = ,,?,, ;,,,, a p b, a = p a = &b a + + a a- - a a + = n a,, ( 3 ) C,, C, : #include " stdio. h" { char str[ ] = { A, B, C, D, * pc = str, int x = 3191; /* x = 0xc77 * / long y = ; / * y = 0x2412a0 * / printf( " pc[ % d] = % c \ n", 3, * ( pc + 3) ) ; printf( " pc[ % d] = % c \ n", 4, * ( pc + 4) ) ; printf( " pc[ % d] = % c \ n", 8, * ( pc + 8) ) ; 5. 9, str, 4, x ( 2 short ) y ( 4 long ), : pc[ 3] = D pc[ 4] = w pc[ 8] =,,,,,,, pc + 0 str pc + 1 pc + 2 pc + 3 pc + 4 x pc + 5 pc + 6 y pc + 7 pc + 8 pc a,, 5. 10,, a a[ 3 ], a;, a[ 0 ] a[ 1] a[ 2 ],, a[ 0 ] a [ 1 ] a [ 2 ], 83

91 C 4, a a &a[ 0] a [ 0 ] &a [ 0] [ 0 ],, a, &a[ 0 ] a[ 0 ] a[ 0], &a[ 0] [ 0] a[ 0] a[ 1] a[ 2], a[ 0] &a[ 0] [ 0], a[ 1] &a[ 1] [ 0], a[ 2 ] &a[ 2] [ 0], +, : : a[ 0 ] * ( a + 0 ) * a ; a[ i] * ( a + i) ; : ; ;, ; &a[ 1] [ 3] a [ 1 ] + 3 * ( a + 1) + 3 &a[ 2] [ 1] a [ 2 ] + 1 * ( a + 2) + 1 &a[ i] [ j] a[ i] + j * ( a + i) + j, a[ i] [ j] * ( a[ i] + j), * ( * ( a + i) + j) ; i = 0, 1, 2; j = 0, 1, 2, 3, a [ i] * ( a + i), 5. 6 #include " stdio. h" { int a[ 3] [ 4] = {1, 2, 3, 4, 11, 12, 13, 14, 21, 22, 23, 24 ; int i, j; for ( i = 0; i < 3; i + + ) { for( j = 0; j < 4; j + + ) : a[ 0] a[ 1] a[ 2] printf( " % 4d", * ( * ( a + i) + j) ) ; / * a[ i] [ j] * / printf( " \n" ) ; * ( * ( a + i) + j) a[ i] [ j] a a[ 0] [ 0] a[ 0] [ 1] a[ 0] [ 2] a[ 0] [ 3] a[ 1] [ 0] a[ 1] [ 1] a[ 1] [ 2] a[ 1] [ 3] a[ 2] [ 0] a[ 2] [ 1] a[ 2] [ 2] a[ 2] [ 3] a[ 0 ] + 0 a[ 0 ] + 0 a[ 0 ] + 1 a[ 0 ] + 1 a[ 0 ] + 2 a[ 0 ] + 2 a[ 0 ] + 3 a[ 0 ] + 3 a[ 1 ] + 0 a[ 0 ] + 4 a[ 1 ] + 1 a[ 0 ] + 5 a[ 1 ] + 2 a[ 0 ] + 6 a[ 1 ] + 3 a[ 0 ] + 7 a[ 2 ] + 0 a[ 0 ] + 8 a[ 2 ] + 1 a[ 0 ] + 9 a[ 2 ] + 2 a[ 0] + 10 a[ 2 ] + 3 a[ 0] + 11 a, ( ), &a[ 1 ] [ 1] a[ 0 ] + 5 &a[ 0] [ 0] + 5, a + 5, 84

92 5, * ( a + 5) a[ 5], 5. 7 #include " stdio. h" { int a[ 3] [ 4] = {1, 2, 3, 4, 11, 12, 13, 14, 21, 22, 23, 24 ; int * p; p = a[ 0] ; while( p < a[ 0] + 12) printf( ( i% 4)? " % 4d" : " \ n% 4d", * p ++ ) ; 5. 6,,, * p + +, p = a[ 0 ] ; p = a;??,, * ( a[ i] + j) * ( * ( a + i) + j) a[ i] [ j] p, ( * p) [ i] 5. 8 #include " stdio. h" { int a[ 3] [ 4] = {1, 2, 3, 4, 11, 12, 13, 14, 21, 22, 23, 24 ; int ( * p) [ 4], i, j; / * p 4 * / p = a; / * p * / printf( " Enter i, j: " ) ; scanf( " % d, % d", &i, &j) ; printf( " a[ % d, % d] = % d \ n", i, j, ( * p + i) [ j] ) ; : Enter i, j: 2, 3 a[ 2, 3] = 24 t[ 3] [ 4] [ 5], t[ 0] t[ 1] t[ 2 ], 4, 5 ;, t [ 0] t[ 0] [ 0] t[ 0] [ 1] t[ 0] [ 2] t[ 0] [ 3], t[ i] [ j] * ( t[ i] + j), t[ i] [ j] [ k] * ( * ( t[ i] + j) + k) * ( * ( * ( t + i) + j) + k), i = 0, 1, 2; j = 0, 1, 2, 3; k = 0, 1, 2, 3, char, C,, 85

93 C ( 1 ) \0, 5. 9 #include " stdio. h" { char s[ ] = " Good morning! " ; char * p; p = s; /* p s * / printf( " s string is % s\ n", s) ; printf( " ( 1) p string is % s \ n", p) ; p = s + 5; /* p s 5 m * / printf( " ( 2) p string is % s \ n", p) ; : s string is Good morning! ( 1) p string is Good morning! ( 2) p string is morning! % s p s, s ; p s, ( 2 ), : char * str = " I am a student. " ;,, ( 3 ) : char * str; str = " I am a student. " ;,, : char s[ 80] ; s = " I am a student. " ;, str = " I am a student. " ;, 86

94 #include " stdio. h" { char ch, * pc = " C language program. ", * p; printf( " Enter a character: " ) ; scanf( " % c", &ch) ; /* * / p = pc; /* p * / while( * p! = \0&& * p! = ch) /* p * / p + + ; /* p * / if ( * p = = ch) /*,, p * / else printf( " The character % c is % d-th \ n", ch, p-pc + 1) ; printf( " The character not found \ n" ) ; : Enter a character: e The character e is 10-th : Enter a character: s The character not fount #include " stdio. h" #include " string. h" /* ( 1 ) * /, { char str[ 80], * p, * q, t; printf( " Enter a string: " ) ; scanf( " % s", str) ; / * * / for( p = str, q = p + strlen( str) -1; p < q; p + +, q - - ) { t = * p; /*,, p \0 * / / * p, q \ 0,, p q, p, q, p > = q * / * p = * q; * q = t; printf( " The reversed string is: % s \ n", str) ; : Enter a string: abcdefgh / * * /

95 C The reversed string is: hgfedcba strlen( str), str string. h ,, : * [ ] ;,,, p, 3, int : int * p[ 3] ;, : float * px[ 5], * py[ 3], data[ 5] [ 10], a, b, * pa = &a; : int b[ 3] [ 4], * pb[ 3] ; b[ 3] [ 4] b[ 0 ] b[ 1 ] b [ 2] 3, 3 3 : 88 pb[ 0] = b[ 0] ; pb[ 1] = b[ 1] ; pb[ 2] = b[ 2] ; pb #include " stdio. h" { int b[ 3] [ 4], * pb[ 3], i, j; for( i = 0; i < 3; i + + ) / * * / for( j = 0; j < 4; j + + ) b[ i] [ j] = ( i + 1) * ( j + 1) ; pb[ 0] = b[ 0] ; / * 3 * / pb[ 1] = b[ 1] ; pb[ 2] = b[ 2] ; for( i = 0; i < 3; i + + ) / * * / { for( j = 0; j < 4; j + + ) printf( " b[ % d] [ % d] = % d ", i, j, * ( pb[ i] + j) ) ; printf( " \n" ) ;