c / intermediate
Snippet
Multi-dimensional Variable Length Arrays
Variable Length Arrays (VLA) allow function parameters to specify dimensions that are determined at runtime. This makes passing multi-dimensional arrays much cleaner than using manual pointer arithmetic or flattened arrays.
snippet.c
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#include <stdio.h>void fill_matrix(int rows, int cols, int matrix[rows][cols]) {for (int i = 0; i < rows; i++) {for (int j = 0; j < cols; j++) {matrix[i][j] = i * cols + j;}}}int main() {int r = 3, c = 4;int my_matrix[r][c];fill_matrix(r, c, my_matrix);printf("Element [2][3]: %d\n", my_matrix[2][3]);return 0;}
Breakdown
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int matrix[rows][cols]
The compiler uses the 'rows' and 'cols' parameters to calculate correct offsets for the 2D array.
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int my_matrix[r][c];
Allocates the array on the stack with dimensions specified by variables r and c.