C Program to Remove First Occurrence of a Character in a String

In this article, we will show you, How to write a C Program to Remove First Occurrence of a Character in a String with example.

C Program to Remove First 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 remove the first occurrence of a character inside a string.

/* C Program to Remove First Occurrence of a Character in a String */
 
#include <stdio.h>
#include <string.h>
 
int main()
{
  	char str[100], ch;
  	int i, len;
  	i = 0;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Remove :  ");
  	scanf("%c", &ch);
  	
	len = strlen(str);
	   	
  	while(i < len && str[i] != ch)
	{
		i++;
	}  
  	
  	while(i < len)
  	{
  		str[i] = str[i + 1];
		i++;  
	}
	printf("\n The Final String after Removing First occurrence of '%c' = %s ", ch, str);
	
  	return 0;
}

OUTPUT

ANALYSIS
User entered values
str[] = Hello
ch = l

While Loop First Iteration: while(i < len && str[i] != ch)
=> while(0 < 5 && H != l) – Condition is True
i will be incremented

Second Iteration: while(1 < 5 && e != l) – Condition is True
i will be incremented

Third Iteration: while(2 < 5 && l != l)
Condition is False. So, it will exit from the While Loop. Remember, i value is 2
i will be incremented
Next, compiler will enter into second while loop

Second While Loop First Iteration: while(i < len)
=> while(2 < 5) – Condition is True
str[i] = str[i + 1]
str[2] = str[3]
str[2] = l
i will be incremented

Second Iteration: while(3 < 5)
str[3] = str[4]
str[3] = o
i will be incremented

Third Iteration: while(4 < 5)
str[4] = str[5]
str[4] = ‘\0’
i will be incremented

Fourth Iteration: while(5 < 5)
Condition Fails. So, compiler will exit from the While Loop

Next, we used the printf statement to print the final string.

printf("\n The Final String after Removing First occurrence of '%c' = %s ", ch, str);

C Program to Remove First Occurrence of a Character in a String Example 2

This program is same as above. Here, we just replaced the While Loop with For Loop. I suggest you to refer For Loop to understand the Loop iterations.

/* C Program to Remove First Occurrence of a Character in a String */
 
#include <stdio.h>
#include <string.h>
 
int main()
{
  	char str[100], ch;
  	int i, len;
 
  	printf("\n Please Enter any String :  ");
  	gets(str);
  	
  	printf("\n Please Enter the Character that you want to Remove :  ");
  	scanf("%c", &ch);
  	
	len = strlen(str);
	   	
  	for(i = 0; i < len && str[i] != ch; i++);
  	
  	while(i < len)
  	{
  		str[i] = str[i + 1];
		i++;  
	}
	printf("\n The Final String after Removing First occurrence of '%c' = %s ", ch, str);
	
  	return 0;
}

OUTPUT

C Program to Remove First Occurrence of a Character in a String Example 3

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

/* C Program to Remove First Occurrence of a Character in a String */
 
#include <stdio.h>
#include <string.h>

void Remove_FirstOccurrence(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 Remove :  ");
  	scanf("%c", &ch);
  	
	Remove_FirstOccurrence(str, ch);
	
	printf("\n The Final String after Removing First occurrence of '%c' = %s ", ch, str);
	
  	return 0;
}

void Remove_FirstOccurrence(char *str, char ch)
{
	int i, len;
	
	len = strlen(str);
	
	for(i = 0; i < len && str[i] != ch; i++);
  	
  	while(i < len)
  	{
  		str[i] = str[i + 1];
		i++;  
	}
}

OUTPUT

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