Example: Maximum Element in Column - With Input Validation

// Maximum Element in Column - With Input Validation
#include <stdio.h>
#include <limits.h> // Required for INT_MIN

// Function to find the maximum element in a specified column with validation
// Parameters:
//   matrix: The 2D array (matrix)
//   rows: Number of rows in the matrix
//   cols: Number of columns in the matrix
//   target_column: The 0-indexed column to search
// Returns: The maximum element in the target_column, or INT_MIN if validation fails.
int findMaxInColumnValidated(int matrix[][4], int rows, int cols, int target_column) {
    // Step 1: Validate the target_column index
    if (target_column < 0 || target_column >= cols) {
        printf("Error: Invalid column index (%d). Must be between 0 and %d.\n", target_column, cols - 1);
        return INT_MIN; // Return a distinct error value
    }

    // Step 2: Validate if there are any rows to process
    if (rows <= 0) {
        printf("Error: Matrix has no rows.\n");
        return INT_MIN;
    }

    // Step 3: Initialize max_element with the first element of the target column
    int max_element = matrix[0][target_column];

    // Step 4: Iterate through the rows to find the maximum
    for (int i = 1; i < rows; i++) {
        if (matrix[i][target_column] > max_element) {
            max_element = matrix[i][target_column];
        }
    }
    return max_element;
}

int main() {
    // Step 1: Define the matrix and its dimensions
    int matrix[3][4] = {
        {10, 20, 15, 30},
        {25, 12, 18, 22},
        {14, 35, 28, 16}
    };
    int rows = 3;
    int cols = 4;
    int valid_column = 1;
    int invalid_column_high = 4; // Out of bounds
    int invalid_column_low = -1; // Out of bounds

    printf("Matrix:\n");
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            printf("%4d", matrix[i][j]);
        }
        printf("\n");
    }
    printf("\n");

    // Step 2: Test with a valid column
    int result_valid = findMaxInColumnValidated(matrix, rows, cols, valid_column);
    if (result_valid != INT_MIN) {
        printf("Maximum element in valid column %d is: %d\n", valid_column, result_valid);
    }

    // Step 3: Test with an invalid column (too high)
    int result_invalid_high = findMaxInColumnValidated(matrix, rows, cols, invalid_column_high);
    if (result_invalid_high != INT_MIN) {
        printf("Maximum element in invalid column %d is: %d\n", invalid_column_high, result_invalid_high);
    }

    // Step 4: Test with an invalid column (too low)
    int result_invalid_low = findMaxInColumnValidated(matrix, rows, cols, invalid_column_low);
    if (result_invalid_low != INT_MIN) {
        printf("Maximum element in invalid column %d is: %d\n", invalid_column_low, result_invalid_low);
    }

    return 0;
}