C program to replace first occurrence of a character in a string

Write a C program to replace first occurrence of a character with another character in a string. How to replace first occurrence of a character with another character in a string using loop in C programming. Program to replace first occurrence of a character with another in string in C.

Example:
Input string: I love programming.
Input character to replace: .
Input character to replace with: !
Output after replace: I love programming!

Required knowledge

Basic C programming, Loop, String, Function

Logic to replace first occurrence of a character

To replace the first occurrence of a character with another character the one out of two things we need to do is find the first occurrence of the character to be replaced. After locating the index of character to be replaced change its value to new character.

Program to replace first occurrence of a character

/**
 * C program to replace first occurrence of a character with another in a string
 */

#include <stdio.h>
#define MAX_SIZE 100 //Maximum size of the string


/* Function declaration */
void replaceFirst(char * string, char toReplace, char replaceWith);



int main()
{
    char string[MAX_SIZE], toReplace, replaceWith;

    printf("Enter any string: ");
    gets(string);

    printf("Enter character to replace: ");
    scanf(" %c", &toReplace);

    printf("Enter character to replace '%c' with: ", toReplace);
    scanf(" %c", &replaceWith);


    printf("\nString before replacing: %s\n", string);

    replaceFirst(string, toReplace, replaceWith);

    printf("String after replacing: %s\n", string);

    return 0;
}




/**
 * Replaces the first occurrence of a character
 * with another in given string.
 */
void replaceFirst(char * string, char toReplace, char replaceWith)
{
    int i=0;

    /* Runs till the end of string */
    while(string[i] != '\0')
    {
        /* If an occurrence of character is found */
        if(string[i] == toReplace)
        {
            string[i] = replaceWith;
            break;
        }

        i++;
    }
}

Happy coding ;)