Example: Matrix Transpose using Pointers in C

// Matrix Transpose using Pointers
#include <stdio.h>

#define ROWS 3
#define COLS 3

int main() {
    int matrix[ROWS][COLS] = {
        {1, 2, 3},
        {4, 5, 6},
        {7, 8, 9}
    };
    int transpose[COLS][ROWS]; // Transposed matrix will have COLS rows and ROWS columns

    // Step 1: Print the original matrix
    printf("Original Matrix:\n");
    for (int i = 0; i < ROWS; i++) {
        for (int j = 0; j < COLS; j++) {
            // Accessing matrix[i][j] using pointer arithmetic
            printf("%d ", *(*(matrix + i) + j));
        }
        printf("\n");
    }

    // Step 2: Calculate the transpose using pointers
    for (int i = 0; i < ROWS; i++) {
        for (int j = 0; j < COLS; j++) {
            // Assign element at matrix[i][j] to transpose[j][i]
            // Original: *( *(matrix + i) + j ) points to matrix[i][j]
            // Transposed: *( *(transpose + j) + i ) points to transpose[j][i]
            *(*(transpose + j) + i) = *(*(matrix + i) + j);
        }
    }

    // Step 3: Print the transposed matrix
    printf("\nTransposed Matrix:\n");
    for (int i = 0; i < COLS; i++) { // Iterate COLS for rows of transpose
        for (int j = 0; j < ROWS; j++) { // Iterate ROWS for columns of transpose
            // Accessing transpose[i][j] using pointer arithmetic
            printf("%d ", *(*(transpose + i) + j));
        }
        printf("\n");
    }

    return 0;
}