C/C++ - 数组与指针

Transcription

1 C/C++

2 Table of contents

3

4 float candy [ 365]; char code [12]; int states [50]; 2

5 int array [6] = {1, 2, 4, 6, 8, 10}; 3

6 // day_mon1.c: # include <stdio.h> # define MONTHS 12 int main ( void ) { int i; int days [ MONTHS ] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; for ( i = 0; i < MONTHS ; i ++) printf (" Month %2d has %2d days.\n", i+1, days [i]); return 0; } 4

7 Month 1 has 31 days. Month 2 has 28 days. Month 3 has 31 days. Month 4 has 30 days. Month 5 has 31 days. Month 6 has 30 days. Month 7 has 31 days. Month 8 has 31 days. Month 9 has 30 days. Month 10 has 31 days. Month 11 has 30 days. Month 12 has 31 days. 5

8 const // day_mon1_const.c: # include <stdio.h> # define MONTHS 12 int main ( void ) { const int days [ MONTHS ] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; int i; for ( i = 0; i < MONTHS ; i ++) printf (" Month %2d has %2d days.\n", i+1, days [i]); return 0; } 6

9 const const 7

10 ... // no_data.c: # include <stdio.h> # define SIZE 6 int main ( void ) { int no_data [ SIZE ]; int i; printf ("%2s%14 s\n", "i", " no_data [i]"); for ( i = 0; i < SIZE ; i ++) printf ("%2d%14 d\n", i, no_data [i]); return 0; } 8

11 ... i no_data [i]

12 ... 10

13 ... // some_data.c: # include <stdio.h> # define SIZE 6 int main ( void ) { int some_ data [ SIZE ] = {11, 12}; int i; printf ("%2s%14 s\n", "i", " no_data [i]"); for ( i = 0; i < SIZE ; i ++) printf ("%2d%14 d\n", i, some_data [i]); return 0; } 11

14 ... i no_data [i]

15

16 ... 14

17 ... # include <stdio.h> # define MONTHS 12 int main ( void ) { int i; const int days [] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; for ( i = 0; i < sizeof days / sizeof days [0]; i ++) printf (" Month %2d has %2d days.\n", i+1, days [i]); return 0; } 15

18 ... sizeof days sizeof days[0] 16

19 C99 C int arr [6] = {0, 0, 0, 0, 0, 212}; 17

20 C99 C int arr [6] = {0, 0, 0, 0, 0, 212}; C99 int arr [6] = {[ 5] = 212}; // set arr [5] to

21 C99 // designate.c # include <stdio.h> # define MONTHS 12 int main ( void ) { int days [ MONTHS ] = {31, 28, [4] = 31, 30, 31, [1] = 29}; int i; for ( i = 0; i < MONTHS ; i ++) printf (" Month %2d has %2d days.\n", i+1, days [i]); return 0; } 18

22 C99 Month 1 has 31 days. Month 2 has 29 days. Month 3 has 0 days. Month 4 has 0 days. Month 5 has 31 days. Month 6 has 30 days. Month 7 has 31 days. Month 8 has 0 days. Month 9 has 0 days. Month 10 has 0 days. Month 11 has 0 days. Month 12 has 0 days. 19

23 C

24 C 21

25 int main ( void ) { int arr1 [5] = {1, 2, 3, 4}; int arr2 [5]; } arr2 = arr1 ; // invalid arr2 [5] = arr1 [5]; // OK arr2 [5] = {1, 2, 3, 4}; // invalid 22

26 int arr [20];

27 i // bounds.c # include <stdio.h> # define SIZE 4 int main ( void ) { int value1 = 14, value2 = 88; int arr [ SIZE ]; int i; printf (" value1 = %d, value2 = %d\n", value1, value2 ); for ( i = -1; i <= SIZE ; i ++) arr [ i] = 2 * i + 1; for ( i = -1; i < 7; i ++) printf ("%2d %d\n", i, arr [i]); printf (" value1 = %d, value2 = %d\n", 24

28 ii value1, value2 ); } return 0; 25

29 value1 = 14, value2 = value1 = -1, value2 = 9 26

30 int n = 5; int m = 8; float a1 [5]; // OK float a2 [5*2 + 1]; // OK float a3[ sizeof ( int ) + 1]; // OK float a4 [ -1]; // Invalid float a5 [0]; // Invalid float a6 [2.5]; // Invalid float a7 [( int ) 2.5]; //OK, float to int float a8[n]; // C99 OK float a9[m]; // C99 OK 27

31

32 28

33 i /* rain. c -- finds yearly totals, yearly average, and monthly average for several years of rainfall data */ # include <stdio.h> # define MONTHS 12 // number of months in a year # define YEARS 5 // number of years of data int main ( void ) { // initializing rainfall data for const float rain [ YEARS ][ MONTHS ] = { { 4.3,4.3,4.3,3.0,2.0,1.2,0.2,0.2,0.4,2.4,3.5,6.6 }, { 8.5,8.2,1.2,1.6,2.4,0.0,5.2,0.9,0.3,0.9,1.4,7.3 }, { 9.1,8.5,6.7,4.3,2.1,0.8,0.2,0.2,1.1,2.3,6.1,8.4 }, { 7.2,9.9,8.4,3.3,1.2,0.8,0.4,0.0,0.6,1.7,4.3,6.2 }, { 7.6,5.6,3.8,2.8,3.8,0.2,0.0,0.0,0.0,1.3,2.6,5.2 } }; int year, month ; float subtot, total ; 29

34 ii printf (" YEAR RAINFALL ( inches )\n"); for ( year = 0, total = 0; year < YEARS ; year ++) { // for each year, sum rainfall for each month for ( month = 0, subtot = 0; month < MONTHS ; month ++) subtot += rain [ year ][ month ]; printf ("%5d %15.1 f\n", year, subtot ); total += subtot ; // total for all years } printf ("\ nthe yearly average is %.1 f inches.\n\n", total / YEARS ); printf (" MONTHLY AVERAGES :\n"); printf (" Jan Feb Mar Apr May Jun "); printf (" Jul Aug Sep Oct Nov Dec \ n"); for ( month = 0; month < MONTHS ; month ++) { // for each month, sum for ( year = 0, subtot =0; year < YEARS ; year ++) 30

35 iii subtot += rain [ year ][ month ]; printf (" %4.1 f", subtot / YEARS ); } printf ("\n"); } return 0; 31

36 YEAR RAINFALL ( inches ) The yearly average is 39.4 inches. MONTHLY AVERAGES : Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

37 sometype ar1 [5] = { val1, val2, val3, val4, val5 }; 33

38 rain[5][12] 5 12 float float 5 34

39 const float rain [ YEARS ][ MONTHS ] = { {4.3,4.3,4.3,3.0,2.0,1.2,0.2,0.2,0.4,2.4,3.5,6.6}, {8.5,8.2,1.2,1.6,2.4,0.0,5.2,0.9,0.3,0.9,1.4,7.3}, {9.1,8.5,6.7,4.3,2.1,0.8,0.2,0.2,1.1,2.3,6.1,8.4}, {7.2,9.9,8.4,3.3,1.2,0.8,0.4,0.0,0.6,1.7,4.3,6.2}, {7.6,5.6,3.8,2.8,3.8,0.2,0.0,0.0,0.0,1.3,2.6,5.2} }; 35

40

41 0 37

42 int box [10][20][30]; box

43

44 39

45 40

46 array array == & array [0]; 40

47 i // pnt_ add. c -- pointer addition # include <stdio.h> # define SIZE 4 int main ( void ) { short dates [ SIZE ]; short * pti ; short index ; double bills [ SIZE ]; double * ptf ; pti = dates ; // assign address of array to pointer ptf = bills ; 41

48 ii printf (" %23 s %14 s\n", " short ", " double "); for ( index = 0; index < SIZE ; index ++) printf (" pointers + %d: %14 p %14 p\n", index, pti + index, ptf + index ); } return 0; 42

49 short double pointers + 0: 0 x7fff5fbff7d0 0 x7fff5fbff7b0 pointers + 1: 0 x7fff5fbff7d2 0 x7fff5fbff7b8 pointers + 2: 0 x7fff5fbff7d4 0 x7fff5fbff7c0 pointers + 3: 0 x7fff5fbff7d6 0 x7fff5fbff7c8 43

50 C 1 44

51 * 1 45

52 dates + 2 == & dates [2]; // *( dates + 2) == dates [2]; // 46

53 C array[n] *(array + n) array n 47

54 *(dates+2) *dates+2 * + (*dates)+2 *( dates + 2) // dates * dates + 2 // dates 2 48

55 /* day_ mon3. c -- uses pointer notation */ # include <stdio.h> # define MONTHS 12 int main ( void ) { int index ; int days [ MONTHS ] = {31,28,31,30,31,30, 31,31,30,31,30,31}; } for ( index = 0; index < MONTHS ; index ++) printf (" Month %2d has %d days.\n", index +1, *( days + index )); // same as days [ index ] return 0; 49

56

57 50

58 int sum ( int * ar) { int i; int total = 0; for ( i = 0; i < 10; i ++) total += ar[i]; } return total ; 51

59 int sum ( int * ar) { int i; int total = 0; for ( i = 0; i < 10; i ++) total += ar[i]; } return total ; 10 51

60 int sum ( int * ar, int n) { int i; int total = 0; for (i = 0; i < n; i ++) total += ar[i]; } return total ; 52

61 int sum ( int * ar, int n) { int i; int total = 0; for (i = 0; i < n; i ++) total += ar[i]; } return total ; 52

62 int sum ( int * ar, int n); int sum ( int *, int ); int sum ( int ar [], int n); int sum ( int [], int ); 53

63 int sum ( int * ar, int n) {... } int sum ( int ar [], int n) {... } 54

64 55

65 i // sum_ arr1. c -- sums the elements of an array # include <stdio.h> # define SIZE 10 int sum ( int ar [], int n); int main ( void ) { int marbles [ SIZE ] = {20,10, 5,39, 4, 16,19,26,31,20}; long answer ; answer = sum ( marbles, SIZE ); printf (" The total number of marbles is % ld.\ n", answer ); 56

66 ii } printf (" The size of marbles is %lu bytes.\n", sizeof marbles ); return 0; int sum ( int *ar, int n) { int i; int total = 0; for (i = 0; i < n; i ++) total += ar[i]; printf (" The size of ar is %lu bytes.\n", sizeof ar); 57

67 iii } return total ; 58

68 The size of ar is 8 bytes. The total number of marbles is 190. The size of marbles is 40 bytes. 59

69 The size of ar is 8 bytes. The total number of marbles is 190. The size of marbles is 40 bytes. marbles 40 marbles 10 int 4 ar 8 ar marbles 59

70 sum() 60

71 61

72 i // sum_ arr2. c -- sums the elements of an array # include <stdio.h> # define SIZE 10 int sump ( int * start, int * end ); int main ( void ) { int marbles [ SIZE ] = {20,10,5,39,4, 16,19,26,31,20}; long answer ; answer = sump ( marbles, marbles + SIZE ); printf (" The total number of marbles is % ld.\ n", answer ); return 0; } 62

73 ii /* use pointer arithmetic */ int sump ( int * start, int * end ) { int total = 0; while ( start < end ) { total += * start ; start ++; } return total ; } 63

74 start marbles total += *start total start++ start 1 64

75 sump() while ( start < end ) end end 65

76 sump() while ( start < end ) end end C 65

77 sump() while ( start < end ) end end C answer = sump ( marbles, marbles + SIZE ); 65

78 end answer = sump ( marbles, marbles + SIZE - 1); 66

79 end answer = sump ( marbles, marbles + SIZE - 1); C marbles+size marbles[size] 66

80 total += * start ; start ++; total += * start ++; * start *start

81 total += * start ; start ++; total += * start ++; * start *start 1 1 total += *start++ total 1 67

82 total += * start ; start ++; total += * start ++; * start *start 1 1 total += *start++ total 1 total += *++start 1 total 67

83 total += * start ; start ++; total += * start ++; * start *start 1 1 total += *start++ total 1 total += *++start 1 total (*start)++ start

84 i // order. c -- precedence in pointer operations # include <stdio.h> int data [2] = {100, 200}; int moredata [2] = {300, 400}; int main ( void ) { int * p1, * p2, * p3; p1 = p2 = data ; p3 = moredata ; printf ("*p1 = %d, *p2 = %d, *p3 = %d\n", *p1, *p2, *p3); 68

85 ii printf ("*p1 ++ = %d, *++ p2 = %d, (* p3)++ = %d\n ", *p1 ++, *++ p2, (* p3)++) ; printf ("*p1 = %d, *p2 = %d, *p3 = %d\n", *p1, *p2, *p3); } return 0; 69

86 *p1 = 100, *p2 = 100, *p3 = 300 *p1 ++ = 100, *++ p2 = 200, (* p3)++ = 300 *p1 = 200, *p2 = 200, *p3 =

87 C ar[i] *( ar+i) ar ar ar++ 71

88

89 int urn [5] = {100,200,300,400,500}; int * ptr, * ptr1, * ptr2 ; 72

90 1 (assignment) & ptr1 = urn ; ptr2 = & urn [2]; double int 73

91 2 ( dereferencing) * 3 & 74

92 4 ptr = urn ptr + 4 &urn[4] 5 ptr = &urn[2] ptr++ ptr urn[3] 75

93 6 ptr = &urn[4] ptr - 2 &urn[2] 7 ptr = &urn[4] ptr-- ptr urn[3] 76

94 8 ptr1 = &urn[2], ptr2 = &urn[4] ptr2 - ptr

95 i // ptr_ops. c -- pointer operations # include <stdio.h> int main ( void ) { int urn [5] = {100,200,300,400,500}; int * ptr1, * ptr2, * ptr3 ; ptr1 = urn ; ptr2 = & urn [2]; printf (" pointer value, dereferenced pointer, pointer address :\n"); printf (" ptr1 = %p, * ptr1 =%d, & ptr1 = %p\n", ptr1, *ptr1, & ptr1 ); ptr3 = ptr1 + 4; 78

96 ii printf ("\ nadding an int to a pointer :\n"); printf (" ptr1 + 4 = %p, *( ptr4 + 3) = %d\n", ptr1 + 4, *( ptr1 + 3)); ptr1 ++; printf ("\ nvalues after ptr1 ++:\ n"); printf (" ptr1 = %p, * ptr1 =%d, & ptr1 = %p\n", ptr1, *ptr1, & ptr1 ); ptr2 - -; printf ("\ nvalues after -- ptr2 :\n"); printf (" ptr2 = %p, * ptr2 = %d, & ptr2 = %p\n", ptr2, *ptr2, & ptr2 ); -- ptr1 ; ++ ptr2 ; 79

97 iii printf ("\ npointers reset to original values :\ n"); printf (" ptr1 = %p, ptr2 = %p\n", ptr1, ptr2 ); printf ("\ nsubtracting one pointer from another :\ n"); printf (" ptr2 = %p, ptr1 = %p, ptr2 - ptr1 = %ld\n", ptr2, ptr1, ptr2 - ptr1 ); printf ("\ nsubtracting an int from a pointer :\ n"); printf (" ptr3 = %p, ptr3-2 = %p\n", ptr3, ptr3-2); } return 0; 80

98 i pointer value, dereferenced pointer, pointer address : ptr1 = 0 x7fff5fbff7c0, * ptr1 =100, & ptr1 = 0 x7fff5fbff7b0 adding an int to a pointer : ptr1 + 4 = 0 x7fff5fbff7d0, *( ptr4 + 3) = 400 values after ptr1 ++: ptr1 = 0 x7fff5fbff7c4, * ptr1 =200, & ptr1 = 0 x7fff5fbff7b0 values after -- ptr2 : ptr2 = 0 x7fff5fbff7c4, * ptr2 = 200, & ptr2 = 0 x7fff5fbff7a8 Pointers reset to original values : 81

99 ii ptr1 = 0 x7fff5fbff7c0, ptr2 = 0 x7fff5fbff7c8 subtracting one pointer from another : ptr2 = 0 x7fff5fbff7c8, ptr1 = 0 x7fff5fbff7c0, ptr2 - ptr1 = 2 subtracting an int from a pointer : ptr3 = 0 x7fff5fbff7d0, ptr3-2 = 0 x7fff5fbff7c8 82

100 C 83

101 int *pt; // *pt = 5; // 84

102 int *pt; // *pt = 5; // *pt = 5 5 pt pt 5 84

103 85

104 malloc() 85

105 int urn [3]; int * ptr1, * ptr2 ; ptr1++; ptr2 = ptr1 + 2; ptr2 = urn + 1; urn++; ptr2 = ptr2 + ptr1; ptr2 = urn * ptr1; 86

106

107 int int int 87

108 88

109 89

110 void add_ to ( double arr [], int n, double val ) { int i; for (i = 0; i < n; i ++) arr [i] += val ; } 90

111 void add_ to ( double arr [], int n, double val ) { int i; for (i = 0; i < n; i ++) arr [i] += val ; } 90

112 ar arr[i]++ 1 void sum ( int arr [], int n) { int i; int sum = 0; for (i = 0; i < n; i ++) sum += arr [i ]++; } 91

113 const ANSI C const void sum ( const int arr [], int n); // void sum ( const int arr [], int n) // { int i; int sum = 0; for (i = 0; i < n; i ++) sum += arr [i]; } arr arr[i]++ 92

114 const const const const const 93

115 const i /* arf.c -- array functions */ # include <stdio.h> # define SIZE 5 void show_ array ( const double ar [], int n); void mult_ array ( double ar [], int n, double mult ) ; int main ( void ) { double dip [ SIZE ] = {20.0, 17.66, 8.2, 15.3, 22.22}; printf (" The original dip array :\n"); show_array (dip, SIZE ); mult_array (dip, SIZE, 2.5) ; 94

116 const ii printf (" The dip array after calling mult_ array :\n"); show_array (dip, SIZE ); } return 0; /* displays array contents */ void show_ array ( const double ar [], int n) { int i; for (i = 0; i < n; i ++) printf (" %8.3 f ", ar[i]); putchar ( \n ); } 95

117 const iii /* multiplies each array member by the same multiplier */ void mult_ array ( double ar [], int n, double mult ) { int i; for (i = 0; i < n; i ++) ar[i] *= mult ; } 96

118 const The original dip array : The dip array after calling mult_ array ():

119 const 1. const const double PI = ; #define # define PI

120 const 2. const 99

121 const const # define MONTHS const int days [ MONTHS ] = {31,28,31,30,31,30, 31,31,30,31,30,31};... days [9] = 44; // 100

122 const double rates [4] = {8.9, 10.1, 9.4, 3. 2}; const double * pd = rates ; //pd *pd = 29.89; // pd [2] = ; // rates [0] = 99.99; // rates pd ++; // pd rates[1] 101

123 const void show_ array ( const double * ar, int n); 102

124 const const (a) double rates [4] = {8.9, 10.1, 9.4, 3. 2}; const double locked [4] = {0.8, 0.7, 0.2, 0.3}; const double * pc = rates ; // pc = locked ; // pc = & rates [3]; // 103

125 const const (b) double rates [4] = {8.9, 10.1, 9.4, 3. 2}; const double locked [4] = {0.8, 0.7, 0.2, 0.3}; double * pnc = rates ; // pnc = locked ; // pnc = & rates [3]; // 104

126 const show_array show_array ( rates, 4); // show_array ( locked, 4); // mult_array mult_array ( rates, 4); // mult_array ( locked, 4); // const const 105

127 const 3. const double rates [4] = {8.9, 10.1, 9.4, 3. 2}; double const * pc = rates ; //pc pc = & rates [3]; // *pc = 2.2; // rates[0] 106

128 const 4. const double rates [4] = {8.9, 10.1, 9.4, 3. 2}; const double const * pc = rates ; pc = & rates [3]; // *pc = 2.2; // 107

129

130 108

131 int zippo [4][2]; // zippo zippo int zippo int 109

132 zippo zippo == &zippo[0] zippo[0] int zippo[0] == &zippo[0][0] zippo zippo[0] zippo == zippo[0] 110

133 1 zippo zipp[0] zippo int zipp[0] int zippo+1 zippo[0]+1 111

134 zippo[0] zippo[0][0] *( zippo [0]) == zippo [0][0] int 112

135 zippo zippo[0] * zippo == zippo [0] zippo [0] == & zippo [0][0] * zippo == & zippo [0][0] *& zippo [0][0] == zippo [0][0] ** zippo == zippo [0][0] 113

136 zippo 114

137 i /* zippo1.c -- zippo info */ # include <stdio.h> int main ( void ) { int zippo [4][2] = { {2,4}, {6,8}, {1,3}, {5,7} }; printf (" zippo = %p, zippo +1 = % p\ n", zippo, zippo +1) ; printf (" zippo [0] = %p, zippo [0]+1 = %p\n", zippo [0], zippo [0]+1) ; printf (" * zippo = %p, * zippo +1 = %p\n", * zippo, * zippo +1) ; printf (" zippo [0][0] = %d\n", zippo [0][0]) ; printf (" * zippo [0] = %d\n", * zippo [0]) ; 115

138 ii printf ("** zippo = %d\n", ** zippo ); printf (" zippo [2][1] = %d\n", zippo [2][1]) ; printf (" *(*( zippo +2) + 1) = %d\n", *(*( zippo +2) + 1) ); } return 0; 116

139 zippo = 5 fbff7b0, zippo + 1 = 5 fbff7b8 zippo [0] = 5 fbff7b0, zippo [0] + 1 = 5 fbff7b4 * zippo = 5 fbff7b0, * zippo + 1 = 5 fbff7b4 zippo [0][0] = 2 * zippo [0] = 2 ** zippo = 2 zippo [2][1] = 3 *(*( zippo +2) + 1) = 3 zippo 1 8 zippo[0]

140 1: *(*(zippo+2)+1) zippo zippo+2 *(zippo+2) *(zippo+2)+1 *(*(zippo+2)+1) zippo[0] zippo[2] zippo[2] zippo[2] zippo[2] 2 zippo[2] 2 118

141 zippo[2][1] 119

142 pz 120

143 int (* pz) [2]; pz int 121

144 int * pax [2]; pax pax * pax int pax int int 122

145 i /* zippo2.c -- zippo info */ # include <stdio.h> int main ( void ) { int zippo [4][2] = { {2,4}, {6,8}, {1,3}, {5,7} }; int (* pz) [2]; pz = zippo ; printf (" pz = %p, pz + 1 = %p\n", pz, pz + 1); printf (" pz [0] = %p, pz [0] + 1 = %p\n", pz [0], pz [0] + 1); printf (" *pz = %p, *pz + 1 = %p\n", *pz, *pz + 1); printf (" pz [0][0] = %d\n", pz [0][0]) ; 123

146 ii printf (" *pz [0] = %d\n", *pz [0]) ; printf ("** pz = %d\n", ** pz); printf (" pz [2][1] = %d\n", pz [2][1]) ; printf (" *(*( pz +2) + 1) = %d\n", *(*( pz +2) + 1)); } return 0; 124

147 pz = 5 fbff7b0, pz + 1 = 5 fbff7b8 pz [0] = 5 fbff7b0, pz [0] + 1 = 5 fbff7b4 *pz = 5 fbff7b0, *pz + 1 = 5 fbff7b4 pz [0][0] = 2 *pz [0] = 2 ** pz = 2 pz [2][1] = 3 *(*( pz +2) + 1) = 3 125

148 pz pz[2][1] zippo [m][n] == *(*( zippo +m)+n) pz[m][n] == *(*( pz+m)+n) 126

149 int double int n = 5; double x; int * pi = &n; double * pd = &x; x = n; // pd = pi; // 127

150 int * pt; int (* pa) [3]; int ar1 [2][3]; int ar2 [3][2]; int ** p2; // pt = & ar1 [0][0]; // int pt = ar1 [0]; // int pa = ar1 ; // int[3] p2 = &pt; // int * 128

151 pt = ar1 ; // pa = ar2 ; // *p2 = ar2 [0]; // int p2 = ar2 ; // pt int ar1 3 int pa 3 int ar2 2 int p2 int ar2 2 int *p2 int ar2[0] ar2[0] ar2[0][0] ar2[0][0] int 129

152 int * p1; const int * p2; const int ** pp2 ; p1 = p2; // const const p2 = p1; // const const pp2 = &p1; // const const const const const const const 130

153 int * p1; const int ** pp2 ; const int n = 13; pp2 = &p1; // * pp2 = &n; // const p1 n *p1 = 10; // const n 131

154 132

155 133

156 i // array2d. c -- functions for 2d arrays # include <stdio.h> # define ROWS 3 # define COLS 4 void sum_rows ( int ar [][ COLS ], int rows ); void sum_cols ( int [][ COLS ], int ); int sum2d ( int (* ar)[ COLS ], int rows ); int main ( void ) { int junk [ ROWS ][ COLS ] = { {2,4,6,8}, {3,5,7,9}, {12,10,8,6} }; 134

157 ii sum_rows (junk, ROWS ); sum_cols (junk, ROWS ); printf (" Sum of all elements = %d\n", sum2d (junk, ROWS )); } return 0; void sum_rows ( int ar [][ COLS ], int rows ) { int r, c, tot ; for ( r = 0; r < rows ; r ++) { tot = 0; for ( c = 0; c < COLS ; c ++) 135

158 iii } } tot += ar[r][c]; printf (" row %d: sum = %d\n", r, tot ); void sum_cols ( int ar [][ COLS ], int rows ) { int r, c, tot ; for ( c = 0; c < COLS ; c ++) { tot = 0; for ( r = 0; r < rows ; r ++) tot += ar[r][c]; printf (" col %d: sum = %d\n", c, tot ); } 136

159 iv } int sum2d ( int ar [][ COLS ], int rows ) { int r, c; int tot = 0; } for ( r = 0; r < rows ; r ++) for ( c = 0; c < COLS ; c ++) tot += ar[r][c]; return tot ; 137

160 row 0: sum = 20 row 1: sum = 24 row 2: sum = 36 col 0: sum = 17 col 1: sum = 19 col 2: sum = 21 col 3: sum = 23 Sum of all elements =

161 ar 4 int 4 139

162 int sum2 ( int ar [][], int rows ); ar[1] ar+1 ar 140

163 int sum2 ( int ar [][], int rows ); ar[1] ar+1 ar int sum2 ( int ar [][4], int rows ); ar 4 int ar

164 int sum2 ( int ar [3][4], int rows ); 3 141

165 n int sum4d ( int ar [][4][5][6], int rows ); 142

166 n int sum4d ( int ar [][4][5][6], int rows ); int sum4d ( int (* ar) [4][5][6], int rows ); ar int 142

167

168 # define COLS 4 int sum2d ( int ar [][ COLS ], int rows ) { int r; int c; int tot = 0; for ( r = 0; r < rows ; r ++) for ( c = 0; c < COLS ; c ++) tot += ar[r][c]; return tot ; } 143

169 int ar1 [5][4]; int ar2 [100][4]; int ar3 [2][4]; tot = sum2d (ar1, 5); tot = sum2d (ar2, 100) ; tot = sum2d (ar3, 2); 144

170 6 5 COLS 5 COLS 145

171 146

172 FORTRAN FORTRAN FORTRAN C FORTRAN FORTRAN 147

173 C99 (VLA) 148

174 C99 (VLA) int m = 4; int n = 5; double array [m][n]; 148

175 int 149

176 1 int sum2d ( int rows, int cols, int ar[ rows ][ cols ]); rows cols ar int sum2d ( int ar[ rows ][ cols ], int rows, int cols ); int sum2d (int, int, int ar [*][*]) ; 150

177 2 int sum2d ( int rows, int cols, int ar[ rows ][ cols ]) { int r; int c; int tot = 0; for ( r = 0; r < rows ; r ++) for ( c = 0; c < cols ; c ++) tot += ar[r][c]; return tot ; } 151

178 i // vararr2d. c -- functions using VLAs # include <stdio.h> # define ROWS 3 # define COLS 4 int sum2d ( int rows, int cols, int ar[ rows ][ cols ]); int main ( void ) { int i, j; int rs = 3; int cs = 10; int junk [ ROWS ][ COLS ] = { {2,4,6,8}, {3,5,7,9}, {12,10,8,6} }; 152

179 ii int morejunk [ ROWS -1][ COLS +2] = { {20,30,40,50,60,70}, {5,6,7,8,9,10} }; int varr [rs ][ cs ]; // VLA for ( i = 0; i < rs; i ++) for ( j = 0; j < cs; j ++) varr [i][j] = i * j + j; printf ("3x5 array \n"); printf (" Sum of all elements = % d\ n", sum2d (ROWS, COLS, junk )); printf ("2x6 array \n"); printf (" Sum of all elements = % d\ n", 153

180 iii } sum2d (ROWS -1, COLS +2, morejunk )); printf ("3 x10 VLA \n"); printf (" Sum of all elements = % d\ n", sum2d (rs, cs, varr )); return 0; // function with a VLA parameter int sum2d ( int rows, int cols, int ar[ rows ][ cols ]) { int r, c; int tot = 0; for ( r = 0; r < rows ; r ++) for ( c = 0; c < cols ; c ++) tot += ar[r][c]; return tot ; } 154

181 3x5 array Sum of all elements = 80 2x6 array Sum of all elements = x10 VLA Sum of all elements =

182 156

183 { } int thing [10][6]; twoset (10, 6, thing );... void twoset ( int n, int m, int ar[n][m]) //ar m int { int temp [n][m]; //temp nxm int temp [0][0] = 2; // temp 2 ar [0][0] = 2; // thing[0][0] 2 } 157

184

185 int float 158

186 159

187 160

188

189 1 161

190 i // ex01.c # include <stdio.h> void swap ( double * a, double * b); void sort ( double arr [], int n); void print_ arr ( double arr [], int n); int main ( void ) { double arr [7] = {1.1, 2.2, 7.7, 4.4, 5.5, 3.3, 6.6}; print_arr (arr, 7); sort (arr, 7); print_arr (arr, 7); return 0; } void swap ( double * a, double * b) 162

191 ii { } double temp ; temp = *a; *a = *b; *b = temp ; void sort ( double arr [], int n) { int i, j, pos ; for (i = 0; i < n;i ++) { pos = i; for (j = i +1; j < n; j ++) { if(arr [j] < arr [ pos ]) pos = j; } 163

192 iii } } if ( pos!= i) swap (& arr [i], & arr [ pos ]); void print_ arr ( double arr [], int n) { int i; for ( i = 0; i < n; i ++) printf (" %6.2 f ", arr [i]); putchar ( \n ); } 164

193 2 double double source [5] = {1.1, 2.2, 3.3, 4.4, 5.5}; double target1 [5], target2 [ 5]; copy_arr ( source, target1, 5); copy_ptr ( source, target2, 5); 165

194 i // ex02.c # include <stdio.h> # define SIZE 5 void copy_ arr ( double source [], double target [], int n) ; void copy_ ptr ( double * source, double * target, int n) ; void print_ arr ( double arr [], int n); int main ( void ) { double source [5] = {1.1, 2.2, 3.3, 4.4, 5.5}; double target1 [5], target2 [5]; copy_arr ( source, target1, SIZE ); copy_ptr ( source, target2, SIZE ); print_arr ( source, SIZE ); 166

195 ii } print_arr ( target1, SIZE ); print_arr ( target2, SIZE ); return 0; void copy_ arr ( double source [], double target [], int n) { int i; for ( i = 0; i < n; i ++) target [i] = source [i]; } void copy_ ptr ( double * source, double * target, int n) { double * ptr1 = source ; double * ptr2 = target ; 167

196 iii } while ( ptr1 < source + n) * ptr2 ++ = * ptr1 ++; void print_ arr ( double arr [], int n) { int i; for ( i = 0; i < n; i ++) printf (" %6.2 f ", arr [i]); putchar ( \n ); } 168

197

198 i // ex03.c # include <stdio.h> void copy_ arr ( double source [], double target [], int n) ; void print_ arr ( double arr [], int n); int main ( void ) { double source [7] = {1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7}; double target [3]; copy_arr ( source +2, target, 3); print_arr ( source, 7); print_arr ( target, 3); return 0; } 170

199 ii void copy_ arr ( double source [], double target [], int n) { int i; for ( i = 0; i < n; i ++) target [i] = source [i]; } void print_ arr ( double arr [], int n) { int i; for ( i = 0; i < n; i ++) printf (" %6.2 f ", arr [i]); putchar ( \n ); } 171

200 4 double 172

201 i // ex04.c # include <stdio.h> void max_ arr1d ( double * arr, int n, double * max, int * index ); int main ( void ) { double array [4] = {2.0, -1.0,5.0,5.0}; double max ; int index ; max_arr1d ( array, 4, &max, & index ); printf (" the maximum value of array is % f " " which is located at %d- th element.\ n", max, index +1) ; return 0; } 173

202 ii void max_ arr1d ( double * arr, int n, double * max, int * index ) { int i; * max = arr [0]; * index = 0; for (i = 1; i < n; i ++) { if (* max < arr [i]) { * max = arr [i]; * index = i; } } } 174

203 5 175

204 i // ex05.c # include <stdio.h> void sum_ arr1d ( int * arr1, int * arr2, int * arr3, int n); void print_ arr1d ( int arr1d [], int n); int main ( void ) { int arr1 [4] = {2,4,5,8}; int arr2 [4] = {1,0,4,6}; int arr3 [4]; sum_arr1d (arr1, arr2, arr3, 4); print_arr1d (arr1, 4); print_arr1d (arr2, 4); print_arr1d (arr3, 4); return 0; 176

205 ii } void sum_ arr1d ( int * arr1, int * arr2, int * arr3, int n) { int i; for ( i = 0; i < n; i ++) arr3 [i] = arr1 [i] + arr2 [i]; } void print_ arr1d ( int arr1d [], int n) { int i; for ( i = 0; i < n; i ++) printf ("%3d ", arr1d [i]); putchar ( \n ); 177

206 iii } 178

207 6 u = (a 1,a 2,a 3 ) T, v = (b 1,b 2,b 3 ) T u v = a 1 b 1 +a 2 b 2 +a 3 b 3 u v = i j k a 1 a 2 a 3 b 1 b 2 b 3 = (a 2 b 3 a 3 b 2,a 3 b 1 a 1 b 3,a 1 b 2 a 2 b 1 ) T. 179

208 7 5 double

209 // ex07.h # include <stdio.h> # define COLS 5 # define ROWS 3 void input_ array2d ( double arr2d [][ COLS ], int row ); void print_ array1d ( double arr1d [], int n); void print_ array2d ( double arr2d [][ COLS ], int row ); double aver_ array1d ( double * arr1d, int n); void aver_ array2d_ row ( double arr2d [][ COLS ], int row, double average []) ; double aver_ array2d ( double arr2d [][ COLS ], int row ); double max_ array2d ( double arr2d [][ COLS ], int row ); 181

210 i // ex07.c # include " ex07.h" int main ( void ) { double arr2d [ ROWS ][ COLS ]; double average_ row [ ROWS ]; double average, max ; printf (" Please input 3 sets of five double numbers each.\n"); input_array2d ( arr2d, ROWS ); printf (" The array is :\n"); print_array2d ( arr2d, ROWS ); aver_array2d_row ( arr2d, ROWS, average_row ); printf (" average of each row :\n"); 182

211 ii print_ array1d ( average_row, ROWS ); average = aver_ array2d ( arr2d, ROWS ); printf (" average of arr2d is %5.2 f\ n", average ); max = max_array2d ( arr2d, ROWS ); printf (" max of arr2d is %5.2 f\n", max ); } return 0; void input_ array2d ( double arr2d [][ COLS ], int row ) { int r, c; for ( r = 0; r < row ; r ++) for ( c = 0; c < COLS ; c ++) 183

212 iii } scanf ("%lf", & arr2d [r][c]); void print_ array1d ( double arr1d [], int n) { int i; for ( i = 0; i < n; i ++) printf (" %8.2 f", arr1d [i]); putchar ( \n ); } void print_ array2d ( double arr2d [][ COLS ], int row ) { int r; for ( r = 0; r < row ; r ++) print_array1d ( arr2d [r], COLS ); 184

213 iv } double aver_ array1d ( double * arr1d, int n) { int i; double total = 0.0; for ( i = 0; i < n; i ++) total += arr1d [ i]; return total /( double ) n; } void aver_ array2d_ row ( double arr2d [][ COLS ], int row, double average []) { int i; for ( i = 0; i < row ; i ++) 185

214 v } average [i] = aver_array1d ( arr2d [i], COLS ); double aver_ array2d ( double arr2d [][ COLS ], int row ) { int i, j; double total = 0.0; for ( i = 0; i < row ; i ++) for ( j = 0; j < COLS ; j ++) total += arr2d [i][j]; return total /( double ) ( row * COLS ); } double max_ array2d ( double arr2d [][ COLS ], int row ) { int i, j; 186

215 vi } double max = arr2d [0][0]; for ( i = 0; i < row ; i ++) for ( j = 0; j < COLS ; j ++) if ( max < arr2d [i][j]) max = arr2d [i][j]; return max ; 187

216 8 188

217 // ex08.h # include <stdio.h> void input_ array2d ( int row, int col, double arr2d [ row ][ col ]); void print_ array1d ( double arr1d [], int n); void print_ array2d ( int row, int col, double arr2d [ row ][ col ]); double aver_ array1d ( double * arr1d, int n); void aver_ array2d_ row ( int row, int col, double arr2d [ row ][ col ], double average []) ; double aver_ array2d ( int row, int col, double arr2d [ row ][ col ]); double max_ array2d ( int row, int col, double arr2d [ row ][ col ]); 189

218 i // ex08.c # include " ex08.h" int main ( void ) { int row = 3; int col = 5; double arr2d [ row ][ col ]; double average_ row [ row ]; double average, max ; printf (" Please input 3 sets of five double numbers each.\n"); input_array2d (row, col, arr2d ); printf (" The array is :\n"); print_array2d (row, col, arr2d ); aver_array2d_row (row, col, arr2d, average_row ); 190

219 ii printf (" average of each row :\n"); print_ array1d ( average_row, row ); average = aver_ array2d ( row, col, arr2d ); printf (" average of arr2d is %5.2 f\ n", average ); max = max_array2d (row, col, arr2d ); printf (" max of arr2d is %5.2 f\n", max ); } return 0; void input_ array2d ( int row, int col, double arr2d [ row ][ col ]) { 191

220 iii } int r, c; for ( r = 0; r < row ; r ++) for ( c = 0; c < col ; c ++) scanf ("%lf", & arr2d [r][c]); void print_ array2d ( int row, int col, double arr2d [ row ][ col ]) { int r; for ( r = 0; r < row ; r ++) print_array1d ( arr2d [r], col ); } void print_ array1d ( double arr1d [], int n) { 192

221 iv } int i; for ( i = 0; i < n; i ++) printf (" %8.2 f", arr1d [i]); putchar ( \n ); double aver_ array1d ( double * arr1d, int n) { int i; double total = 0.0; for ( i = 0; i < n; i ++) total += arr1d [ i]; return total /( double ) n; } 193

222 v void aver_ array2d_ row ( int row, int col, double arr2d [ row ][ col ], double average []) { int i; for ( i = 0; i < row ; i ++) average [i] = aver_array1d ( arr2d [i], col ); } double aver_ array2d ( int row, int col, double arr2d [ row ][ col ]) { int i, j; double total = 0.0; for ( i = 0; i < row ; i ++) for ( j = 0; j < col ; j ++) total += arr2d [i][j]; 194

223 vi } return total /( double ) ( row * col ); double max_ array2d ( int row, int col, double arr2d [ row ][ col ]) { int i, j; double max = arr2d [0][0]; for ( i = 0; i < row ; i ++) for ( j = 0; j < col ; j ++) if ( max < arr2d [i][j]) max = arr2d [i][j]; return max ; } 195

224 9 196

225 // ex09.h # include <stdio.h> # define ROWS 3 # define COLS 5 void input_ array2d ( int row, int col, double * arr2d ); void print_ array1d ( double * arr1d, int n); void print_ array2d ( int row, int col, double * arr2d ); void aver_ array2d_ row ( int row, int col, double * arr2d, double * average ); double aver_ array2d ( int row, int col, double * arr2d ); double max_ array2d ( int row, int col, double * arr2d ); 197

226 i // ex09.c # include " ex09.h" int main ( void ) { double arr2d [ ROWS * COLS ]; double average_ row [ ROWS ]; double average ; double max ; printf (" Please input 3 sets of five double numbers each.\n"); input_array2d (ROWS, COLS, arr2d ); printf (" The array is :\n"); print_array2d (ROWS, COLS, arr2d ); 198

227 ii aver_array2d_row (ROWS, COLS, arr2d, average_row ); printf (" average of each row :\n"); print_ array1d ( average_row, ROWS ); average = aver_ array2d ( ROWS, COLS, arr2d ); printf (" average of arr2d is %5.2 f\ n", average ); max = max_array2d (ROWS, COLS, arr2d ); printf (" max of arr2d is %5.2 f\n", max ); } return 0; void input_ array2d ( int row, int col, double * arr2d ) { int i; 199

228 iii } for (i = 0; i < row * col ; i ++) scanf ("%lf", & arr2d [i]); void print_ array1d ( double * arr1d, int n) { int i; for ( i = 0; i < n; i ++) printf (" %8.3 f", arr1d [i]); putchar ( \n ); } void print_ array2d ( int row, int col, double * arr2d ) { int r, c; for (r = 0; r < row ; r ++) { 200

229 iv } } for ( c = 0; c < col ; c ++) printf (" %8.2 f",arr2d [r* col +c]); putchar ( \n ); void aver_ array2d_ row ( int row, int col, double * arr2d, double * average ) { int r, c; double sum ; for (r = 0; r < row ; r ++) { sum = 0.0; for ( c = 0; c < col ; c ++) sum += arr2d [r* col +c]; 201

230 v } } average [ r] = sum / ( double ) col ; double aver_ array2d ( int row, int col, double * arr2d ) { int i; double total = 0.0; for (i = 1; i < row * col ; i ++) total += arr2d [ i]; return total /( double ) ( row * col ); } double max_ array2d ( int row, int col, double * arr2d ) { int i; 202

231 vi } double max = arr2d [0]; for (i = 1; i < row * col ; i ++) if ( max < arr2d [i]) max = arr2d [i]; return max ; 203