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April 20, 2020 08:09
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dynamic allocate memory to 2d or 3d array
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#include <unistd.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
int **malloc_2d(int row, int col) | |
{ | |
if (row < 0 || col < 0) | |
return NULL; | |
int *array = (int *)malloc(row * col * sizeof(int)); | |
int **p = (int **)malloc(row * sizeof(int *)); | |
if (array == NULL || p == NULL) | |
return NULL; | |
int *ptr = array; | |
for (int i = 0; i < row; i++) | |
{ | |
p[i] = ptr; | |
ptr += col; | |
} | |
return p; | |
} | |
int ***malloc_3d(int a, int b, int c) | |
{ | |
int *array = (int *)malloc(a * b * c * sizeof(int)); | |
int **pp = (int **)malloc(a * b * sizeof(int *)); | |
int ***p = (int ***)malloc(a * sizeof(int *)); | |
if (array == NULL || p == NULL || pp == NULL) | |
return NULL; | |
int *ptr2 = array; | |
for (int i = 0; i < a * b; i++) | |
{ | |
pp[i] = ptr2; | |
ptr2 += c; | |
} | |
for (int i = 0; i < a; i++) | |
{ | |
p[i] = &pp[i * b]; | |
} | |
return p; | |
} | |
int main() | |
{ | |
// int **array = malloc_2d(3, 4); | |
// for (size_t i = 0; i < 3; i++) | |
// { | |
// for (size_t j = 0; j < 4; j++) | |
// { | |
// array[i][j] = i * 10 + j; | |
// } | |
// } | |
// for (size_t i = 0; i < 3; i++) | |
// { | |
// for (size_t j = 0; j < 4; j++) | |
// { | |
// printf("%d ", array[i][j]); | |
// } | |
// printf("\n"); | |
// } | |
int ***array = malloc_3d(3, 4, 5); | |
if (array == NULL) | |
return 0; | |
for (size_t i = 0; i < 3; i++) | |
{ | |
for (size_t j = 0; j < 4; j++) | |
{ | |
for (size_t k = 0; k < 5; k++) | |
{ | |
array[i][j][k] = i * 100 + j * 10 + k; | |
} | |
} | |
} | |
for (size_t i = 0; i < 3; i++) | |
{ | |
for (size_t j = 0; j < 4; j++) | |
{ | |
for (size_t k = 0; k < 5; k++) | |
{ | |
printf("%d ", array[i][j][k]); | |
} | |
} | |
} | |
return 0; | |
} |
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