#include <stdio.h>
  
  void swap(int a,int b)
    { int temp;
      temp=a;
      a=b;
      b=temp;
    }
  
  void swapa(int *pa,int  *pb)
    { int temp;
      temp=*pa;
      *pa=*pb;
      *pb=temp;
    }
  
  void swapr(int& a,int&  b) // Does not work in C
    { int temp;              // but works in C++
      temp=a;
      a=b;
      b=temp;
    }
  
  void passp(int a[])
    { int temp;
      temp=a[0];
      a[0]=a[1];
      a[1]=temp;
    }
  
  int main(void)
  { int a,b,c[2];
    a=3;
    b=5;
    swap(a,b);
    printf("After swap: a is %d b is %d\n",a,b);
    swapa(&a,&b);
    printf("After swapa: a is %d b is %d\n",a,b);
    swapr(a,b);
    printf("After swapr: a is %d b is %d\n",a,b);
  
    c[0]=0;
    c[1]=1;
    passp(c);
    printf("After passp: c[0] is %d c[1] is %d\n",c[0],c[1]);
  }