Access 2D array using pointer Dry Run in C

Access 2D array using pointer is an interactive C dry run visualizer from the Pointersarrays programs section. Study the source code, then use the execution controls to follow each step, variable update, highlighted line, and console output.

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Access 2D array using pointer Program Code

#include <stdio.h>
int main() {
    int i, j;
    int matrix[3][4] = {
        {1, 2, 3, 4},
        {5, 6, 7, 8},
        {9, 10, 11, 12}
    };
    
    int rows = 3, cols = 4;
    
    printf("Accessing 2D array using pointers:\n\n");
    
    // Method 1: Using row pointer
    int (*rowPtr)[4] = matrix;  // Pointer to array of 4 ints
    
    for(i = 0; i < rows; i++) {
        for(j = 0; j < cols; j++) {
            printf("%2d ", rowPtr[i][j]);
        }
        printf("\n");
    }
    
    // Method 2: Using single pointer with offset calculation
    printf("\nUsing single pointer (row-major order):\n");
    int *ptr = &matrix[0][0];
    for(i = 0; i < rows * cols; i++) {
        printf("%2d ", *(ptr + i));
        if((i+1) % cols == 0) printf("\n");
    }
    
    // Method 3: Pointer to element using arithmetic
    printf("\nUsing *(*(matrix + i) + j):\n");
    for(i = 0; i < rows; i++) {
        for(j = 0; j < cols; j++) {
            printf("%2d ", *(*(matrix + i) + j));
        }
        printf("\n");
    }
    
    return 0;
}

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