Example: String Sorting using qsort in C

// String Sorting using qsort
#include <stdio.h>
#include <stdlib.h> // For qsort
#include <string.h> // For strcmp

// Comparison function required by qsort
// It takes two void pointers to elements to be compared
int compareStrings(const void *a, const void *b) {
    // Cast the void pointers to char pointers (pointers to strings)
    const char *str1 = *(const char **)a;
    const char *str2 = *(const char **)b;

    // Use strcmp to compare the actual strings
    return strcmp(str1, str2);
}

int main() {
    // Step 1: Define the array of strings
    char *strings[] = {"banana", "apple", "cherry", "date", "grape"};
    int n = sizeof(strings) / sizeof(strings[0]);

    printf("Original strings:\n");
    for (int i = 0; i < n; i++) {
        printf("%s\n", strings[i]);
    }
    printf("\n");

    // Step 2: Call qsort to sort the array of strings
    // Parameters for qsort:
    // 1. Base address of the array (strings)
    // 2. Number of elements in the array (n)
    // 3. Size of each element (sizeof(strings[0]) which is sizeof(char*))
    // 4. Pointer to the comparison function (compareStrings)
    qsort(strings, n, sizeof(strings[0]), compareStrings);

    // Step 3: Print the sorted strings
    printf("Sorted strings (qsort):\n");
    for (int i = 0; i < n; i++) {
        printf("%s\n", strings[i]);
    }

    return 0;
}