C program to concatenate two strings

Interview Preparation

In this tutorial we are going to learn writing C program to concatenate two given strings. To concatenate we have multiple ways to do.

Here we will see two ways first one using library function strcat() and second one using manually using loop concepts.

How our string concatenate program will work?

  • Our program will take two string as an input.
  • Now using strcat() function available in string.h header file we can concatenate two string.
  • strcat() function takes two string as a parameter and return one string after concatenation.
  • We can also concatenate manually by copying one character to another string.

C program to concatenate two strings without using library function strcat

#include <stdio.h>
#include <string.h>
int main()
{
    char str1[256], str2[256];
    int i,len;
printf("C Program to Concatenate two String”);
    printf("Enter the first string: ");
    scanf("%s",str1);
    printf("Enter the second string: ");
    scanf("%s",str2);
    len=strlen(str1);
    for(int j=0;str2[j]!='\0';j++)
    {
        str1[len]=str2[j];
        len++;
    }
   printf("After concatenation the string is : %s", str1);
return 0;
}

Output

C program to concatenate two strings without using library function strcat

C program to concatenate two strings using strcat()

#include <stdio.h>
#include<string.h>
int main()
{
  char str1[256],str2[256];
printf("C Program to Concatenate two String”);
printf("Enter the first string : ");
scanf("%s", str1);
printf("\nEnter the second string :");
scanf("%s",str2);
strcat(str1,str2);
printf("After concatenation the string is : %s",str1);
    return 0;
}

Output

C program to concatenate two strings using strcat()

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