Concatenate two strings

Q. Write a program to concatenate two strings without using the strcat() function.

Ans.

/*program to concatenate two strings without using the strcat() function*/

#include<stdio.h>

#include<conio.h>

#include<string.h>

int main()

{

 int x=0,y=0,z=0;

 char str1[20],str2[20];

 char add[40];

 printf("Enter first string : ");

 gets(str1);

 printf("\nEnter second string : ");

 gets(str2);

 while(str1[x]!=NULL)

 {

   add[z]=str1[x];

   x++;

   z++;

 }

 while(str2[y]!=NULL)

 {

   add[z]=str1[y];

   y++;

   z++;

 }

 add[z]=NULL;

 puts(add);
 getch();

 return 0;

}

/***************Output******************

Enter first string : Input

Enter second string : Device

InputDevice

*****************************************/