Ví dụ về Hoán Vị

#include<iostream.h>
#include<conio.h>
void InKt (CharCh)
{
 cout<<ch<endl;
}
int ucln (int a, int b)
{
 int ucln=a;
 while (a% ucln!=0||b% ucln !=0)
 ucln --;
 return ucln;
}
void hoanvi1(int a1, int b)
{
 int t=a;
 a1=b1;
 b1=t;
}
void hoanvi2 (int &a2, int &b2)
{
 int t=a2;
 a2=b2;
 b2=t;
}
void hoanvi3 (int *a3, int *b3)
{
 int t=*a3;
 *a3=*b3;
 *b3=t;
}
int main()
{
 char ch="*";
 int x=5, y=10;
 int u=5, v=6;
 InKt (ch);
 InKt ('A');
 cout<<ucln(x, y);
 hoanvi1(u,v);
 hoanvi2(u,v);
 hoanvi3(&u, &v)
 getch();
 return0;
}