C Program to concatinate two string with out using Builtin functions.

/*  string concatnation without using build functions  */                                

#include<stdio.h>

#include<conio.h>

main()

{

  int i,j,k;

  char a[20],b[20],c[20],d[20];

  clrscr();

  printf("\n enter the three strings");

  scanf("%s%s%s",a,b,c);

  for(i=0;a[i]!='\0';i++)

  {

   d[i]=a[i];

   d[i]=' ';

  }

  for(j=0;b[j]!='\0';j++)

  {

   d[i+j+1]=b[j];

   d[i+j+1]=' ';

  }

  for(k=0;c[k]!='\0';k++)

  {

   d[i+j+k+2]=c[k];

   d[i+j+k+2]='\0';

  }

  printf("\n the combined string is....%s",d);

  getch();

}