C program to compare two strings without using library function

In this article we will learn to implement a C program to compare two strings without using library function. A C program is provided below to compare two strings without using predefined function.

Program is as follows:

#include<stdio.h>
#include<string.h>
int main()
{
	char str[20];
	printf("Enter a string: ");
	scanf("%s", str);
	char newstr[20];
	printf("Enter another string: ");
	scanf("%s", newstr);
	int flag = 0;
	//We assume that both strings will be of same length
	int i = 0;
	while(i < strlen(str))
	{
		if(str[i] != newstr[i])
		{
			flag = 1;
			break;
		}
		i++;
	}
	if(flag == 0)
		printf("Strings are equal");
	else
		printf("Strings are not equal");
	return 0;
}

Input and output for the above program is as follows:

Enter a string: madam
Enter another string: madam
Strings are equal

Suryateja Pericherla

Suryateja Pericherla, at present is a Research Scholar (full-time Ph.D.) in the Dept. of Computer Science & Systems Engineering at Andhra University, Visakhapatnam. Previously worked as an Associate Professor in the Dept. of CSE at Vishnu Institute of Technology, India.

He has 11+ years of teaching experience and is an individual researcher whose research interests are Cloud Computing, Internet of Things, Computer Security, Network Security and Blockchain.

He is a member of professional societies like IEEE, ACM, CSI and ISCA. He published several research papers which are indexed by SCIE, WoS, Scopus, Springer and others.