C Program to Sort a String of Characters

Last Updated : 23 Jul, 2025

Sorting a string of characters refers to the process of rearranging all the characters in the given order. In this article, we will learn how to sort a string of characters using the C program.

The most straightforward method to sort a string of characters is by using the qsort() function. Let's take a look at an example:

C 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// Comparator function for qsort
int comp(const void *a, const void *b) {
    return (*(char *)a - *(char *)b);  
}

int main() {
    char s[] = "adfecb";

    // Sort the string using qsort
    qsort(s, strlen(s), sizeof(char), comp);

    printf("%s", s);
    return 0;
}

Output
abcdef

Explanation: The qsort() function needs a comparator that guides it how to compare two values of the given dataset. In this case, it tells how two characters should be compared and the order in which they should be arranged.

C language only provides the built-in method for the quick sort algorithm. If you need any other sorting algorithm, you will have to implement them yourself as shown:

Using Bubble Sort

Bubble Sort is a simple comparison-based sorting algorithm which repeatedly compares adjacent characters and swaps them if they are in the wrong order.

C 
#include <stdio.h>

// Implementation of bubble sort
void bubbleSort(char *s) {
    int n = 0;
    while (s[n] != '\0') n++; 
    for (int i = 0; i < n - 1; i++) {
        for (int j = 0; j < n - i - 1; j++) {
            if (s[j] > s[j + 1]) {
                char temp = s[j];
                s[j] = s[j + 1];
                s[j + 1] = temp;
            }
        }
    }
}

int main() {
    char s[] = "adfecb";

    // Sort the string using Bubble Sort
    bubbleSort(s);

    printf("%s", s);
    return 0;
}

Output
abcdef

Using Selection Sort

Selection Sort is another comparison-based sorting algorithm that works by finding the smallest character from the unsorted portion of the string and swapping it with the first unsorted character. This process is repeated until the entire string is sorted.

C 
#include <stdio.h>

// Implementation of selection sort
void selSort(char *s) {
    int n = 0;
    while (s[n] != '\0') n++;
    for (int i = 0; i < n - 1; i++) {
        int minIndex = i;
        for (int j = i + 1; j < n; j++) {
            if (s[j] < s[minIndex]) {
                minIndex = j;
            }
        }
        char temp = s[minIndex];
        s[minIndex] = s[i];
        s[i] = temp;
    }
}
int main() {
    char s[] = "adfecb";
  
  	// Sort the string using Selection Sort
    selSort(s);
  
    printf("%s", s);
    return 0;
}

Output
abcdef
Comment

Explore