Swapping two strings in c++

Swapping two strings is an interesting program , here is the c++ code

******************* Start of Program ************************

// Swapping two strings

#include"iostream.h"
#include"conio.h"
#include"stdio.h"

void main()
{
clrscr();
char str1[20],str2[20],swap[20];
cout<<"Enter 1st string :: ";
gets(str1);
cout<<"Enter 2nd string :: ";
gets(str2);

int i=0;

while(str1[i]!='\0')
{
swap[i]=str1[i];
i++;
}

swap[i]='\0';


int j=0;

while(str2[j]!='\0')
{
str1[j]=str2[j];
j++;
}

str1[j]='\0';

j=0;
while(j{
str2[j]=swap[j];
j++;
}
str2[j]='\0';

cout<<"\n\nAfter Swapping ::";
cout<<"\n\nString 1 is :: "<cout<<"\nString 2 is :: "<
getch();
}

******************* END ************************