Example: Find Middle Max and Min using qsort in C

// Find Middle Max and Min using qsort
#include <stdio.h>
#include <stdlib.h> // Required for qsort

// Comparison function for qsort (for ascending order)
int compareIntegers(const void *a, const void *b) {
    return (*(int*)a - *(int*)b);
}

int main() {
    // Step 1: Get array size from user
    int n;
    printf("Enter the number of elements (min 3): ");
    scanf("%d", &n);

    if (n < 3) {
        printf("Please enter at least 3 elements to find middle max/min.\n");
        return 1; // Indicate an error
    }

    int arr[n]; // Declare array of size n (VLA - C99 feature)

    // Step 2: Get array elements from user
    printf("Enter %d integers:\n", n);
    for (int i = 0; i < n; i++) {
        printf("Element %d: ", i + 1);
        scanf("%d", &arr[i]);
    }

    // Step 3: Sort the array using qsort
    // qsort(base, num, size, compar)
    // base: pointer to the first element of the array
    // num: number of elements in the array
    // size: size of each element in bytes
    // compar: pointer to a comparison function
    qsort(arr, n, sizeof(int), compareIntegers);

    // Step 4: Extract middle minimum and middle maximum
    int middleMin = arr[1];       // Second element (0-indexed)
    int middleMax = arr[n - 2];   // Second to last element

    // Step 5: Print the results
    printf("\nSorted Array: ");
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");

    printf("Middle Minimum (Second Smallest): %d\n", middleMin);
    printf("Middle Maximum (Second Largest): %d\n", middleMax);

    return 0;
}