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

Write a C program to replace last occurrence of a character with another in a given string. How to replace last occurrence of a character with another character in a given string using functions in C programming. Program to replace last occurrence of a character with another character in C.

Example:
Input string: Do you love programming.
Input character to replace: .
Input character to replace with: ?
Output after replace: Do you love programming?

Required knowledge

Basic C programming, Loop, String, Function

Logic to replace last occurrence of a character

We have already seen how easily we can replace first occurrence of a character with another. Here also we will be using same concept we used in previous program. What we need to do is find the last occurrence of the character and change its value to the new value.

Program to replace last occurrence of a character

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

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


/* Function declaration */
void replaceLast(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);

    replaceLast(string, toReplace, replaceWith);

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

    return 0;
}




/**
 * Replaces the last occurrence of a character
 * with another in given string.
 */
void replaceLast(char * string, char toReplace, char replaceWith)
{
    int i, index;

    index = -1;
    i = 0;

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

        i++;
    }

    if(index != -1)
    {
        string[index] = replaceWith;
    }
}

Happy coding ;)