C Program to find All Occurrence of a Character in a String

Write a C Program to find All Occurrence of a Character in a String with an example.

C Program to find All Occurrence of a Character in a String Example 1

This program allows the user to enter a string (or character array), and a character value. Next, it will search and find all the occurrences of a character inside this string using the If Else Statement.

#include <stdio.h>
#include <string.h>
 
int main()
{
  	char str[100], ch;
  	int i;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Search for :  ");
  	scanf("%c", &ch);
  	
  	for(i = 0; i <= strlen(str); i++)
  	{
  		if(str[i] == ch)  
		{
  			printf("\n '%c' is Found at Position %d ", ch, i + 1);
 		}
	}
	
  	return 0;
}

First, we used For Loop to iterate each and every character in a String.

for(i = 0; i <= strlen(str); i++)
{
	if(str[i] == ch)  
	{
		printf("\n '%c' is Found at Position %d ", ch, i + 1);   	
	}
}

str[] = tutorial gateway
ch = t

For Loop First Iteration: for(i = 0; i <= strlen(str); i++)
The condition is True because 0 <= 16.

Within the C Programming While Loop, we used the If statement to check whether the str[0] is equal to a user-specified character or not

if(str[i] == ch) => if(t == t)

The above condition is True. So, the compiler will execute the printf statement inside the If block.

Here, i is the index position (start with zero), and i + 1 is the actual position.

Second Iteration: for(i = 1; 1 <= 16; 1++) – The condition is True because 1 <= 16.

if(str[i] == ch) => if(t == l) – condition is false. So, i will increment.

Third Iteration: for(i = 2; 2 <= 16; 2++)

if(str[i] == ch) => if(t == t) – condition is True. So, the compiler will execute the printf statement inside the If block.

Do the same for the remaining iterations.

C Program to find All Occurrence of a Character in a String Example 2

This program to find all occurrences of a character is the same as above. Here, we just replaced the For Loop with the While Loop.

#include <stdio.h>
#include <string.h>
 
int main()
{
  	char str[100], ch;
  	int i;
	i = 0;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Search for :  ");
  	scanf("%c", &ch);
  	
  	while(str[i] != '\0')
  	{
  		if(str[i] == ch)  
		{
  			printf("\n '%c' is Found at Position %d ", ch, i + 1);
 		}
 		i++;
	}
	
  	return 0;
}

 Please Enter any String :  Hello World

 Please Enter the Character that you want to Search for :  l

 'l' is Found at Position 3 
 'l' is Found at Position 4 
 'l' is Found at Position 10

Program to find All Occurrence of a Character in a String Example 3

This program is the same as the first example, but this time we used the Functions concept to separate the logic.

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

void Find_AllOccurrence(char str[], char ch);

int main()
{
  	char str[100], ch;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Search for :  ");
  	scanf("%c", &ch);
  	
  	Find_AllOccurrence(str, ch);
	
  	return 0;
}

void Find_AllOccurrence(char str[], char ch)
{
	int i;

	for(i = 0; str[i] != '\0'; i++)
	{
		if(str[i] == ch)
		{
			printf("\n '%c' is Found at Position %d ", ch, i + 1);
		}  
	}
}

 Please Enter any String :  welcome to tutorial gateway

 Please Enter the Character that you want to Search for :  t

 't' is Found at Position 9 
 't' is Found at Position 12 
 't' is Found at Position 14 
 't' is Found at Position 23