C program to compare, concatenate and append strings using user defined functions

Join Our Newsletter - Tips, Contests and Other Updates

Thank you for Signing Up

Please correct the marked field(s) below.

Email

Name

1,true,6,Contact Email,2 1,false,1,First Name,2 1,false,1,Last Name,2

In this article we will learn to implement a C program to compare, concatenate and append strings. A C program is provided below to read two strings and perform comparison, concatenation and append operations.

Program is as follows:

/*
 * C program to implement the following string functions using user defined functions:
 * i. To concatenate two strings
 * ii. To append a string to another string
 * iii. To compare two strings
 * Author: P.S.SuryaTeja
*/
#include <stdio.h>
#include <conio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

void concat(char *str1, char *str2)
{
	char str[40];
	int str1length, str2length;
	int i;
	str1length = strlen(str1);
	str2length = strlen(str2);
	for(i = 0; i < str1length; i++)
	{
		str[i] = *str1;
		str1++;
	}
	while(i < str1length + str2length)
	{
		str[i] = *str2;
		str2++;
		i++;
	}
	str[i] = '\0';
	printf("\nResult of concatenation is: ");
	puts(str);
}

void append(char *str1, char *str2)
{
	int str1length, str2length;
	int i;
	char *tempstr;
	tempstr = str1;
	str1length = strlen(str1);
	str2length = strlen(str2);
	for(i = 0; i < str1length; i++)
		str1++;
	for(i = 0; i < str2length; i++)
	{
		*str1 = *str2;
		str1++;
		str2++;
	}
	*str1 = '\0';
	printf("\nResult of appending is: ");
	puts(tempstr);
}

void compare(char *str1, char *str2)
{
	int str1length, str2length;
	int i, flag = 0;
	str1length = strlen(str1);
	str2length = strlen(str2);
	if(str1length != str2length)
		printf("\nBoth strings are not equal");
	else
	{
		for(i = 0; i < str1length; i++)
		{
			if(*str1 != *str2)
				flag = 1;
			str1++;
			str2++;
		}
		if(flag == 0)
			printf("\nBoth strings are equal");
		else
		{
			printf("\nBoth strings are not equal");
		}
	}
}

int main(int argc, char **argv)
{
	char str1[20], str2[20], str3[20];
	printf("Enter string 1: ");
	gets(str1);
	printf("Enter string 2: ");
	gets(str2);
	strcpy(str3,str1);
	printf("\n");
	concat(str1, str2);
	printf("\n");
	append(str1, str2);
	printf("\n");
	compare(str3, str2);
    getch();
    return 0;
}

Input and output for the above program is as follows:

Enter string 1: hai
Enter string 2: hai


Result of concatenation is: haihai


Result of appending is: haihai


Both 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.