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copied!<p>A 2D array is an 1D array of 1D arrays. As an array is simply a pointer, an array of arrays is an array of pointers. So, you use <code>malloc</code> to allocate an array of pointers (each representing a collumn), then use it again to allocate the individual arrays (each representing a row).</p> <p>To expand/shrink the array, you use <code>realloc</code><a href="http://www.cplusplus.com/reference/clibrary/cstdlib/realloc/" rel="nofollow noreferrer">(reference)</a>. Here's an example code:</p> <pre><code>#include <stdlib.h> #include <stdio.h> int** alloc_matrix(int w, int h) { int** matrix; matrix = (int**) malloc(sizeof(int*) * h); for(int i = 0; i < h; i++) { matrix[i] = (int*) malloc(sizeof(int) * w); } return matrix; } void realloc_matrix(int*** matrix, int new_w, int new_h) { *matrix = (int**) realloc((void *)*matrix, sizeof(int*) * new_h); for(int i = 0; i < new_h; i++) { (*matrix)[i] = (int*) realloc((void *)(*matrix)[i], sizeof(int) * new_w); } } int main(int argc, char* argv[]) { // Allocating matrix int** m = alloc_matrix(10, 15); // Filling with some data for(int y = 0; y < 15; y++) { for(int x = 0; x < 10; x++) { m[y][x] = y * x; // Notice the index is [y][x] - NOT [x][y]! } } // Printing for(int y = 0; y < 15; y++) { for(int x = 0; x < 10; x++) { printf("%d\t", m[y][x]); // Notice the index is [y][x] - NOT [x][y]! } printf("\n"); } // Reallocating realloc_matrix(&m, 20, 10); // Filling with some data for(int y = 0; y < 10; y++) { for(int x = 0; x < 20; x++) { m[y][x] = y * x; // Notice the index is [y][x] - NOT [x][y]! } } // Printing for(int y = 0; y < 10; y++) { for(int x = 0; x < 20; x++) { printf("%d\t", m[y][x]); // Notice the index is [y][x] - NOT [x][y]! } printf("\n"); } } </code></pre> <p>I'm sorry if I've got anything wrong. My C-fu is kinda rusty :)</p>

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