SWAP pointers

This works on my C52:

#include <stdio.h>
#include <reg52.h>

char *swapdata (char **destination, char **SourceLine)
{
  char *temp;
  temp=*SourceLine;
  *SourceLine=*destination;
  *destination=temp;
  printf("in function string = %s - %s\n",*destination,*SourceLine);
  return temp;
}

void main(void){
  char *p_test1,*p_test2;
  char test1[] ="test 1";
  char test2[] ="test 2";
  char *result;

  TI = 1;

  p_test1 = test1;
  p_test2 = test2;
  printf("string = %s - %s - %s\n",p_test1,p_test2,result);
  result=swapdata(&p_test1,&p_test2);
  printf("string = %s - %s - %s\n",p_test1,p_test2,result);

  while(1) ;
}

Ignore the lines:

 #include <reg52.h>
  TI = 1;