C Program to Replace Last Occurrence of a Character in a String

C program to replace the last occurrence of a character in a string; Through this tutorial, we will learn how to replace last occurrence of a character in a string using for loop, while loop and functions in c programs.

Programs and Algorithm To Replace Last Occurrence of a Character in a String in C

• Algorithm To Replace Last Occurrence of a Character in a String
• C Program To Replace Last Occurrence of a Character in a String using For Loop
• C Program To Replace Last Occurrence of a Character in a String using While Loop
• C Program To Replace Last Occurrence of a Character in a String using Function

Algorithm To Replace Last Occurrence of a Character in a String

Use the following algorithm to write a program to replace last occurrence of a character with in a string; as follows:

1. Input string from user, store it in some variable.
2. Input character to replace and character new character from user, store it in some variables.
3. Iterate a loop from start of string str to end.
4. Inside the loop, swap old character with new character and terminate the loop.
5. Print result.

C Program To Replace Last Occurrence of a Character in a String using For Loop

/* C Program to Replace Last Occurrence of a Character in a String */

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

int main()
{
  	char str[100], ch, Newch;
  	int i, index;
  	index = -1;

  	printf("\n Please Enter any String :  ");
  	gets(str);

    printf("Enter a character replace: ");
  	scanf("%c", &ch);

  	getchar();

  	printf("\nEnter character to replace  %c with : ",ch);
  	scanf("%c", &Newch);

  	for(i = 0; str[i] != '\0'; i++)
  	{
  		if(str[i] == ch)
		{
  			index = i;
 		}
	}

	if(index != -1)
  	{
  		str[index] = Newch;
	}

 printf("\nafter replace:%s",str);

  	return 0;
}

The output of the above c program; as follows:

Please Enter any String :  hate
Enter a character replace: h
Enter character to replace  h with : v
after replace:vate

C Program To Replace Last Occurrence of a Character in a String using While Loop

/* C Program to Replace Last Occurrence of a Character in a String */

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

int main()
{
  	char str[100], ch, Newch;
  	int i, index;
  	index = -1;
  	i = 0;

  	printf("\n Please Enter any String :  ");
  	gets(str);

    printf("Enter a character replace: ");
  	scanf("%c", &ch);
  	getchar();

  	printf("\nEnter character to replace  %c with : ",ch);
  	scanf("%c", &Newch);

  	while(i <= strlen(str))
  	{
  		if(str[i] == ch)
		{
  			index = i;
 		}
 		i++;
	}

	if(index != -1)
  	{
  		str[index] = Newch;
	}

	printf("\nafter replace:%s",str);

  	return 0;
}

The output of the above c program; as follows:

Please Enter any String :  proramming
Enter a character replace: r
Enter character to replace  r with : l
after replace:prolamming

C Program To Replace Last Occurrence of a Character in a String using Function

/* C Program to Replace Last Occurrence of a Character in a String */

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

void Replace_LastOccurrence(char *str, char ch, char Newch);

int main()
{
  	char str[100], ch, Newch;
  	int i, index;
  	index = -1;

  	printf("\n Please Enter any String :  ");
  	gets(str);

  	printf("Enter a character replace: ");
  	scanf("%c", &ch);

  	getchar();

    printf("\nEnter character to replace  %c with : ",ch);
  	scanf("%c", &Newch);

  	Replace_LastOccurrence(str, ch, Newch);

	printf("\nafter replace:%s",str);

  	return 0;
}

void Replace_LastOccurrence(char *str, char ch, char Newch)
{
	int i, index;
  	index = -1;

	for(i = 0; str[i] != '\0'; i++)
	{
		if(str[i] == ch)
		{
			index = i;
		}
	}

	if(index != -1)
  	{
  		str[index] = Newch;
	}
}

The output of the above c program; as follows:

Please Enter any String :  hello
Enter a character replace: l
Enter character to replace  l with : r
after replace:helro

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