Summary of ref and out use in C #

Ref is the address of the pass parameter, out is the return value, the two have some similarities, but there are different points.

You must assign a value to a variable before you use Ref.

The Out function empties the variable, even if the variable is already assigned, and all out referenced variables are assigned when the function is exited, and ref references can be modified or unmodified.

The difference can be referred to the following code:

using System;
class TestApp
{
　static void outTest(out int x, out int y)
　{//离开这个函数前，必须对x和y赋值，否则会报错。
　　//y = x;
　　//上面这行会报错，因为使用了out后，x和y都清空了，需要重新赋值，即使调用函数前赋过值也不行
　　x = 1;
　　y = 2;
　}
　static void refTest(ref int x, ref int y)
　{
　　x = 1;
　　y = x;
　}
　public static void Main()
　{
　　//out test
　　int a,b;
　　//out使用前，变量可以不赋值
　　outTest(out a, out b);
　　Console.WriteLine("a={0};b={1}",a,b);
　　int c=11,d=22;
　　outTest(out c, out d);
　　Console.WriteLine("c={0};d={1}",c,d);
　　//ref test
　　int m,n;
　　//refTest(ref m, ref n);
　　//上面这行会出错，ref使用前，变量必须赋值
　　int o=11,p=22;
　　refTest(ref o, ref p);
　　Console.WriteLine("o={0};p={1}",o,p);
　}
}