using ref keyword we can swap 2 number's

emaple
class swap
{
public void add(ref int a,ref int b)
{
int z;
z=a;
a=b;
b=z;
}
}
class swapdemo
{
static void main()
{
int x=10,y=5;
ankush obj=new ankush();
Console.writeline{"befor value's"+a+","+b};
obj.swap(ref x, ref y);
Console.writeline("after values"+a+","+b);
}
}