C Program to Compare Two Strings

In this article, We will show you, How to write a C Program to Compare Two Strings without using strcmp function. We can compare two string in multiple way, but we will discuss three different approaches: using For Loop, While Loop, and Functions.

C Program to Compare Two Strings without using strcmp()

This program allows the user to enter two string values or two character array. Next, it will use For Loop to iterate each and every character present in that string, and compares individual characters

/* C program to Compare Two Strings without using strcmp() */
 
#include <stdio.h>
#include <string.h>

int main()
{
  	char Str1[100], Str2[100];
  	int result, i;
 
  	printf("\n Please Enter the First String :  ");
  	gets(Str1);
  	
  	printf("\n Please Enter the Second String :  ");
  	gets(Str2);
  	
  	for(i = 0; Str1[i] == Str2[i] && Str1[i] == '\0'; i++);
		   
  	if(Str1[i] < Str2[i])
   	{
   		printf("\n str1 is Less than str2");
	}
	else if(Str1[i] > Str2[i])
   	{
   		printf("\n str2 is Less than str1");
	}
	else
   	{
   		printf("\n str1 is Equal to str2");
	}
  	
  	return 0;
}

OUTPUT

Let me insert two different strings

two more different strings

C Program to Compare Two Strings Using While Loop

This program is same as above but this time we are using While loop (Just replacing For Loop with While Loop). I suggest you to refer While Loop to understand the loop Iteration.

/* C program to Compare Two Strings without using library function */
 
#include <stdio.h>
#include <string.h>

int main()
{
  	char Str1[100], Str2[100];
  	int result, i;
 	i = 0;
 	
  	printf("\n Please Enter the First String :  ");
  	gets(Str1);
  	
  	printf("\n Please Enter the Second String :  ");
  	gets(Str2);
  	
  	while(Str1[i] == Str2[i] && Str1[i] == '\0')
	  	i++;
		   
  	if(Str1[i] < Str2[i])
   	{
   		printf("\n str1 is Less than str2");
	}
	else if(Str1[i] > Str2[i])
   	{
   		printf("\n str2 is Less than str1");
	}
	else
   	{
   		printf("\n str1 is Equal to str2");
	}
  	
  	return 0;
}

OUTPUT

C program to Compare Two Strings Using Functions

This program is same as above but this time we are using Functions concept to separate the logic from main program.

/* C program to Compare Two Strings without using library function */
 
#include <stdio.h>
#include <string.h>

int Compare_Strings(char *Str1, char *Str2);
 
int main()
{
  	char Str1[100], Str2[100];
  	int result;
 
  	printf("\n Please Enter the First String :  ");
  	gets(Str1);
  	
  	printf("\n Please Enter the Second String :  ");
  	gets(Str2);
  	
  	result = Compare_Strings(Str1, Str2);
  	
  	if(result < 0)
   	{
   		printf("\n str1 is Less than str2");
	}
	else if(result > 0)
   	{
   		printf("\n str2 is Less than str1");
	}
	else
   	{
   		printf("\n str1 is Equal to str2");
	}
  	
  	return 0;
}
int Compare_Strings(char *Str1, char *Str2)
{
	int i = 0;
  	while(Str1[i] == Str2[i])
  	{
  		if(Str1[i] == '\0' && Str2[i] == '\0')
	  		break;
		i++;
	}
	return Str1[i] - Str2[i];
}

OUTPUT

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