Relationship between Pointers and Arrays

In C, arrays and pointers are closely related. The name of an array is essentially a pointer to the first element of the array. For example, if you have an array int arr[10];, the name arr can be used as a pointer to the first element, i.e., arr is equivalent to &arr[0].

Here are some key points:

Array Name as Pointer: The name of an array acts like a pointer to its first element.
Pointer Arithmetic: You can perform arithmetic operations on pointers to traverse the array.
Access Elements: Elements of an array can be accessed using both array notation (arr[i]) and pointer notation (*(arr + i)).

Example in C:

#include <stdio.h>

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    int *ptr = arr; // Pointer to the first element of the array

    for (int i = 0; i < 5; i++) {
        // Accessing elements using both array and pointer notation
        printf("arr[%d] = %d, *(ptr + %d) = %d\n", i, arr[i], i, *(ptr + i));
    }

    return 0;
}

Program to Print Transpose of a 2D Matrix

Here is a C program to read a 2D matrix from the user and print its transpose:

#include <stdio.h>

#define MAX_ROWS 10
#define MAX_COLS 10

int main() {
    int matrix[MAX_ROWS][MAX_COLS];
    int transpose[MAX_COLS][MAX_ROWS];
    int rows, cols;

    // Getting matrix dimensions from the user
    printf("Enter the number of rows and columns of the matrix: ");
    scanf("%d %d", &rows, &cols);

    // Reading the matrix elements from the user
    printf("Enter the elements of the matrix:\n");
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            printf("Element [%d][%d]: ", i, j);
            scanf("%d", &matrix[i][j]);
        }
    }

    // Calculating the transpose of the matrix
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            transpose[j][i] = matrix[i][j];
        }
    }

    // Printing the transpose of the matrix
    printf("\nTranspose of the matrix:\n");
    for (int i = 0; i < cols; i++) {
        for (int j = 0; j < rows; j++) {
            printf("%d ", transpose[i][j]);
        }
        printf("\n");
    }

    return 0;
}

Explanation

Matrix Input: The program first takes the number of rows and columns of the matrix from the user and then reads the matrix elements.
Transpose Calculation: The transpose of the matrix is calculated by swapping rows with columns.
Matrix Output: Finally, the transposed matrix is printed.

Comments:

The matrix array stores the original matrix.
The transpose array stores the transposed matrix.
Nested loops are used to read the matrix elements and calculate the transpose.
The outer loop runs through each row, and the inner loop runs through each column.