C C

Transcription

1 C C

2 char 5. 2/101 C

3 1. 3/101 C

4 C = 5 (F 32). 9 F C 4/101 C

5 1 // fal2cel.c: Convert Fah temperature to Cel temperature 2 #include<stdio.h> 3 int main(void) 4 { 5 float fah, cel; 6 printf("please input the Fah temperature:\n"); 7 scanf("%f", &fah); 8 cel = (fah - 32.) * 5./9.; 9 printf("%.2f F = %.2f C\n", fah, cel); 10 return 0; 11 } 5/101 C

6 $ gcc fah2cel.c $./a.out Please input the Fahrenheit temperature: F = C 6/101 C

7 float fah, cel; float %f %.2f scanf %f scanf &fah fah fah 7/101 C

8 scanf() printf() scanf() printf() 8/101 C

9 2. 9/101 C

10 /101 C

11 a b 11/101 C

12 12/101 C

13 C 12/101 C

14 #define #define 13/101 C

15 price.c 1 #include<stdio.h> 2 #define PRICE int main(void) 4 { 5 int num, total; 6 num = 10; 7 total = num * PRICE; 8 printf("total=%d\n", total); 9 return 0; 10 } 14/101 C

16 15/101 C

17 16/101 C

18 a 3 17/101 C

19 18/101 C

20 /101 C

21 int signed _Bool long void _Complex short unsigned char float double _Imaginary 20/101 C

22 int long short unsigned signed char # $ % * float double long double _Bool true false _Complex _Imaginary 21/101 C

23 3. 22/101 C

24 /101 C

25 : : /101 C

26 int int 25/101 C

27 int 1 // int_max_min.c: print INT_MIN and INT_MAX 2 #include<stdio.h> 3 #include<limits.h> 4 int main(void) 5 { 6 printf("range of int is %d ~ %d\n", INT_MIN, INT_MAX); 7 printf("sizeof int = %lu bytes\n", sizeof(int) ); 8 return 0; 9 } 26/101 C

28 int $ gcc int_max_min.c $./a.out range of int is ~ sizeof int = 4 bytes 27/101 C

29 int int int var; int var1, var2; int 28/101 C

30 int int 1. int n; n = 1; 2. scanf int n; scanf("%d", &n); 3. int n = 1; 29/101 C

31 int int a = 1; int b = 2, c = 3; int d, e = 4; // valid, but not good 30/101 C

32 int 31/101 C

33 int int a; int b=2; a 2 b : 31/101 C

34 int 1 // print1.c: display some properties of printf() 2 #include<stdio.h> 3 int main(void) 4 { 5 int a = 10; 6 int b = 2; 7 printf("doing it right: "); 8 printf("%d - %d = %d\n", a, b, a-b); 9 printf("doing it wrong: "); 10 printf("%d - %d = %d\n", a); 11 return 0; 12 } 32/101 C

35 int $ gcc print1.c $./a.out Doing it right: 10-2 = 8 Doing it wrong: = /101 C

36 int print a %d %d printf 34/101 C

37 C 0x 0X 16 0x10 0X /101 C

38 1 // bases.c: print 100 in decimal, octal and hex 2 #include <stdio.h> 3 int main(void) 4 { 5 int x = 100; 6 printf("dec = %d; octal = %o; hex = %x\n", x, x, x); 7 printf("dec = %d; octal = %#o; hex = %#x\n", x, x, x); 8 return 0; 9 } 36/101 C

39 $ gcc bases.c $./a.out dec = 100; octal = 144; hex = 64 dec = 100; octal = 0144; hex = 0x64 37/101 C

40 %d %o %#o %x %X %#x %#X 38/101 C

41 C 3 int short long unsigned 39/101 C

42 short (int) %hd,%ho,%hx long (int) %ld,%lo,%lx long long (int) C99 %lld,%llo,%llx 40/101 C

43 unsigned %u (int) unsigned C90 %lu long (int) unsigned long long (int) C99 %llu 41/101 C

44 signed short short int signed short signed short int 42/101 C

45 C short int long int CPU long int short 43/101 C

46 44/101 C

47 1 #include <stdio.h> 2 #include <limits.h> 3 int main(void) 4 { 5 int i = INT_MAX; 6 unsigned int j = UINT_MAX; 7 printf("i = %d, i+1 = %d, i+2 = %d\n", 8 i, i+1, i+2); 9 printf("j = %u, j+1 = %u, j+2 = %u\n", 10 j, j+1, j+2); 11 return 0; 12 } 45/101 C

48 $ gcc IntOverflow.c $./a.out i = , i+1 = , i+2 = j = , j+1 = 0, j+2 = 1 46/101 C

49 unsigned int 0 int /101 C

50 4. char 48/101 C

51 char char char a, b, =, +,? char 49/101 C

52 char char char ASCII char 50/101 C

53 char char a, b; char c; 51/101 C

54 A grade char grade = A ; 52/101 C

55 char grade; grade = A ; grade = A; grade = "A"; grade = 65; // char // // // // A 53/101 C

56 ASCII 54/101 C

57 char a = x ; char b = y ; x y ASCII a b a: b: /101 C

58 C 56/101 C

59 printf() %c %d 57/101 C

60 1 // charcode.c: displays code number for a char 2 #include <stdio.h> 3 int main(void) 4 { 5 char c; 6 printf("please input a character:\n"); 7 scanf("%c", &c); 8 printf("the code for %c is %d\n", c, c); 9 return 0; 10 } 58/101 C

61 $ gcc charcode.c $./a.out Please input a character: A the code for A is 65 59/101 C

62 ch %c %d A 65 60/101 C

63 5. 61/101 C

64 e e e e-5 62/101 C

65 C float double long double 63/101 C

66 C float double float C long double double IEEE float IEEE R32.24 double IEEE R /101 C

67 1. (sign) (exponent) 3. (mantissa) 65/101 C

68 : float 66/101 C

69 : double 67/101 C

70 R32.24 R /101 C

71 1. 2 n /101 C

72 24 (9) 10 = (1001) 2, 1 24 float 6 70/101 C

73 /101 C

74 /101 C

75 = 130 = ( ) 2 (0001) 2 72/101 C

76 = 130 = ( ) 2 (0001) = /101 C

77 /101 C

78 = 133 = ( ) 2 ( ) 2 73/101 C

79 = 133 = ( ) 2 ( ) = /101 C

80 , 74/101 C

81 /101 C

82 ( ) 2 = = 6 ( ) 2 = ( ) 2 = /101 C

83 1 // float_double.c: 2 #include <stdio.h> 3 int main(void) 4 { 5 float f1 = 2.2, f2 = 2.25; 6 double g1, g2; 7 g1 = (double) f1; 8 g2 = (double) f2; 9 printf("g1 = %.13f, g2 = %.13f\n", g1, g2); 10 return 0; 11 } 76/101 C

84 $ gcc float_double.c $./a.out g1 = , g2 = /101 C

85 /101 C

86 /101 C

87 /101 C

88 /101 C

89 /101 C

90 e E E+12, 2.87e-3 83/101 C

91 +2.87e e-3 2E // is an integer 3.e12.45E-5 84/101 C

92 1.56 E+12 // wrong double some float some = 4.0 * 2.0; double 64 float 85/101 C

93 f F float 2.3f 3.4e9F l L long double l 1 L 54.3l 4.3E9L 86/101 C

94 1 // float1.c: What is the output? 2 #include<stdio.h> 3 int main(void) 4 { 5 float x = 0.1; 6 if (x == 0.1) 7 printf("if\n"); 8 else if (x == 0.1f) 9 printf("else IF\n"); 10 else 11 printf("else\n"); 12 } 87/101 C

95 $ gcc float1.c $./a.out ELSE IF 88/101 C

96 $ gcc float1.c $./a.out ELSE IF x f f != 0.1f x == 0.1f 88/101 C

97 1 // float2.c: What is the output? 2 #include<stdio.h> 3 int main(void) 4 { 5 float x = 0.1; 6 printf("%lu %lu %lu\n", sizeof(x), sizeof(0.1), sizeof(0.1f)); 7 return 0; 8 } 89/101 C

98 $ gcc float2.c $./a.out /101 C

99 $ gcc float2.c $./a.out /101 C

100 1 // float3.c: What is the output? 2 #include<stdio.h> 3 int main(void) 4 { 5 float x = 0.5; 6 if (x == 0.5) 7 printf("if\n"); 8 else if (x == 0.5f) 9 printf("else IF\n"); 10 else 11 printf("else\n"); 12 } 91/101 C

101 $ gcc float2.c $./a.out IF 92/101 C

102 $ gcc float2.c $./a.out IF x f f == 0.5f x == /101 C

103 %f float double %e %Lf %Le long double 93/101 C

104 1 // showf_pt.c: 2 #include <stdio.h> 3 int main(void) 4 { 5 float a = ; 6 double b = 2.14e9; 7 long double c = 5.32e-5; 8 printf("%f can be written as %e\n", a, a); 9 printf("%f can be written as %e\n", b, b); 10 printf("%lf can be written as %Le\n", c, c); 11 return 0; 12 } 94/101 C

105 $ gcc showf_pt.c $./a.out can be written as e can be written as e can be written as e-05 95/101 C

106 1 #include <stdio.h> 2 #include <limits.h> 3 int main(void) 4 { 5 float toobig = 1e39; 6 printf("toobig = %f\n",toobig); 7 return 0; 8 } 96/101 C

107 $ gcc float_overflow.c $./a.out toobig = inf 97/101 C

108 overflow C inf 98/101 C

109 1 #include <stdio.h> 2 int main(void) 3 { 4 float a,b; 5 a = 2.e20 + 1; 6 b = a - 2.e20; 7 printf("b = %f\n", b); 8 return 0; 9 } 99/101 C

110 $ gcc float_err.c $./a.out b = /101 C

111 2.0e float /101 C