C Program to Sort String

Here we will learn about how to sort any given string (by user at run-time) in ascending and descending order both one by one. Let's first start with how to sort string in ascending order.

C Sort String in Ascending Order

Here we have created a program that will receive any string from the user using gets() function and then will sort the string in ascending order. For example, if the given string is codescracker, then the string after sorting in ascending order will be acccdeekorrs

#include<stdio.h>
#include<conio.h>
#include<string.h>
int main()
{
    char str[100], chTemp;
    int i, j, len;
    printf("Enter any string: ");
    gets(str);
    len = strlen(str);
    for(i=0; i<len; i++)
    {
        for(j=0; j<(len-1); j++)
        {
            if(str[j]>str[j+1])
            {
                chTemp = str[j];
                str[j] = str[j+1];
                str[j+1] = chTemp;
            }
        }
    }
    printf("\nSame string in ascending order:\n%s", str);
    getch();
    return 0;
}

As the program was written under Code::Blocks IDE, therefore after successful build and run, here is the sample run of the above program:

Supply any string say codescracker and press ENTER key to see the same string with sorted its each and every character in ascending order as shown here in the following snapshot:

c program sort string in ascending order

Here are the list of some main steps used in above program:

Receive any string using gets() function
Get the length of string using strlen() function of string.h library and initialize it to any variable say len
Now create a for loop that runs from 0 to one less than the string length
Inside the for loop, create another for loop with another loop variable say j that runs from 0 to two less than the string length to compare each and every character of the string
While comparing, if any character inside the string is greater than the next character, then reverse the character with each other and continue, do this process until each and every character gets arranged in ascending order.
Therefore, we have run the loop two times. One times is upto one less than the string length and second time is upto two less than the string length
In this way, all the character inside the string gets arranged. We only have to print the string value say str

C Sort String in Descending Order

Let's create another program in C, that will also receive any string from user and will sort the given string in descending order as shown in the program given below. For example, if the given string is codescracker, then the string after sorting in descending order will be srrokeedccca:

#include<stdio.h>
#include<conio.h>
#include<string.h>
int main()
{
    char str[100], chTemp;
    int i, j, len;
    printf("Enter any string: ");
    gets(str);
    len = strlen(str);
    for(i=0; i<len; i++)
    {
        for(j=0; j<(len-1); j++)
        {
            if(str[j]<str[j+1])
            {
                chTemp = str[j];
                str[j] = str[j+1];
                str[j+1] = chTemp;
            }
        }
    }
    printf("\nSame string in descending order:\n%s", str);
    getch();
    return 0;
}

Here is the final snapshot of its sample run:

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