matrix_ops.c

/* matrix_ops.c
   Matrix Addition, Multiplication and Transpose using functions and 2D arrays.
   Max allowed size is controlled by MAX.
*/

#include <stdio.h>

#define MAX 10

/* Read an integer within [min..max] (re-prompts until valid) */
int readIntInRange(const char *prompt, int min, int max) {
    int x, rc;
    while (1) {
        printf("%s", prompt);
        rc = scanf("%d", &x);
        if (rc != 1) {
            int ch;
            while ((ch = getchar()) != '\n' && ch != EOF) { } /* clear input */
            printf("Invalid input. Please enter an integer.\n");
            continue;
        }
        if (x < min || x > max) {
            printf("Please enter a value between %d and %d.\n", min, max);
            continue;
        }
        return x;
    }
}

/* Input matrix elements (with per-element validation) */
void inputMatrix(int M[MAX][MAX], int r, int c, char name) {
    printf("Enter elements for matrix %c (%d x %d):\n", name, r, c);
    for (int i = 0; i < r; ++i) {
        for (int j = 0; j < c; ++j) {
            while (1) {
                printf("  %c[%d][%d] = ", name, i + 1, j + 1);
                if (scanf("%d", &M[i][j]) == 1) break;
                int ch;
                while ((ch = getchar()) != '\n' && ch != EOF) { }
                printf("  Invalid number. Try again.\n");
            }
        }
    }
}

/* Print matrix */
void printMatrix(int M[MAX][MAX], int r, int c) {
    for (int i = 0; i < r; ++i) {
        for (int j = 0; j < c; ++j) {
            printf("%d\t", M[i][j]);
        }
        printf("\n");
    }
}

/* Add matrices A and B (assumes r x c). Result stored in R. */
void addMatrices(int A[MAX][MAX], int B[MAX][MAX], int R[MAX][MAX], int r, int c) {
    for (int i = 0; i < r; ++i)
        for (int j = 0; j < c; ++j)
            R[i][j] = A[i][j] + B[i][j];
}

/* Multiply A (r1 x c1) by B (r2 x c2). If possible, store in R and return 1, else return 0. */
int multiplyMatrices(int A[MAX][MAX], int B[MAX][MAX], int R[MAX][MAX],
                     int r1, int c1, int r2, int c2) {
    if (c1 != r2) return 0;
    /* initialize result to 0 */
    for (int i = 0; i < r1; ++i)
        for (int j = 0; j < c2; ++j)
            R[i][j] = 0;

    for (int i = 0; i < r1; ++i) {
        for (int j = 0; j < c2; ++j) {
            for (int k = 0; k < c1; ++k) {
                R[i][j] += A[i][k] * B[k][j];
            }
        }
    }
    return 1;
}

/* Transpose matrix A (r x c) into T (c x r) */
void transposeMatrix(int A[MAX][MAX], int T[MAX][MAX], int r, int c) {
    for (int i = 0; i < c; ++i)      /* ensure all cells of T are set when displayed */
        for (int j = 0; j < r; ++j)
            T[i][j] = 0;

    for (int i = 0; i < r; ++i)
        for (int j = 0; j < c; ++j)
            T[j][i] = A[i][j];
}

int main(void) {
    int A[MAX][MAX], B[MAX][MAX];
    int addR[MAX][MAX], mulR[MAX][MAX], trA[MAX][MAX], trB[MAX][MAX];
    int r1, c1, r2, c2;

    printf("Matrix Operations (max size %dx%d)\n", MAX, MAX);

    r1 = readIntInRange("Enter rows for Matrix A: ", 1, MAX);
    c1 = readIntInRange("Enter columns for Matrix A: ", 1, MAX);
    inputMatrix(A, r1, c1, 'A');

    r2 = readIntInRange("Enter rows for Matrix B: ", 1, MAX);
    c2 = readIntInRange("Enter columns for Matrix B: ", 1, MAX);
    inputMatrix(B, r2, c2, 'B');

    printf("\nMatrix A:\n");
    printMatrix(A, r1, c1);

    printf("\nMatrix B:\n");
    printMatrix(B, r2, c2);

    /* Addition if possible */
    if (r1 == r2 && c1 == c2) {
        addMatrices(A, B, addR, r1, c1);
        printf("\nA + B =\n");
        printMatrix(addR, r1, c1);
    } else {
        printf("\nAddition not possible: dimensions differ (A is %dx%d, B is %dx%d)\n", r1, c1, r2, c2);
    }

    /* Multiplication A x B */
    if (multiplyMatrices(A, B, mulR, r1, c1, r2, c2)) {
        printf("\nA x B =\n");
        printMatrix(mulR, r1, c2);
    } else {
        printf("\nMultiplication not possible: columns of A (%d) != rows of B (%d)\n", c1, r2);
    }

    /* Transposes */
    transposeMatrix(A, trA, r1, c1);
    printf("\nTranspose of A (A^T):\n");
    printMatrix(trA, c1, r1);

    transposeMatrix(B, trB, r2, c2);
    printf("\nTranspose of B (B^T):\n");
    printMatrix(trB, c2, r2);

    return 0;
}