Row-wise and column-wise sum Dry Run in C

Row-wise and column-wise sum 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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Row-wise and column-wise sum Program Code

#include <stdio.h>
int main() {
    int i, j;
    int matrix[4][3] = {
        {1, 2, 3},
        {4, 5, 6},
        {7, 8, 9},
        {10, 11, 12}
    };
    int rows = 4, cols = 3;
    
    printf("Matrix:\n");
    for(i = 0; i < rows; i++) {
        for(j = 0; j < cols; j++) {
            printf("%3d ", matrix[i][j]);
        }
        printf("\n");
    }
    
    // Row-wise sum
    printf("\nRow-wise sums:\n");
    for(i = 0; i < rows; i++) {
        int rowSum = 0;
        for(j = 0; j < cols; j++) {
            rowSum += *(*(matrix + i) + j);
        }
        printf("Row %d: %d\n", i, rowSum);
    }
    
    // Column-wise sum
    printf("\nColumn-wise sums:\n");
    for(j = 0; j < cols; j++) {
        int colSum = 0;
        for(i = 0; i < rows; i++) {
            colSum += *(*(matrix + i) + j);
        }
        printf("Column %d: %d\n", j, colSum);
    }
    
    // Using single pointer approach
    printf("\nUsing single pointer:\n");
    int *ptr = &matrix[0][0];
    for(i = 0; i < rows; i++) {
        int rowSum = 0;
        for(j = 0; j < cols; j++) {
            rowSum += ptr[i * cols + j];
        }
        printf("Row %d: %d\n", i, rowSum);
    }
    
    return 0;
}

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