Swap Numbers call by value and refrence

#include<stdio.h>
#include<conio.h>
 void swap1(int x,int y)
 {
  int z;
  z=x;
  z=y;
  y=z;
  printf("x = %d and y = %d",x,y);
 }
 void swap2(int *p , int *q)
 {
  int c;
  c=*p;
  *p=*q;
  *q=c;
  printf("x = %d and y = %d",*p,*q);
 }
  void main()
{
   int a,b;
   clrscr();
   a=5;
   b=7;
   swap1(a,b);
   printf("After Swap1 Value of a = %d and b = %d \n",a,b);
   swap2(&a,&b);
   printf("After swap2 value of a = %d and b = %d",a,b);
   getch();
 }