Summary of use of ref and out 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)
{//You must assign values to X and y before leaving this function, or you will get an error.
y = x;
The above line error, because after using out, X and Y are emptied, need to be assigned a value, even if the call function before the value is not
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;
Before out use, variables can not be assigned a value
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);
The line above is wrong, and before ref is used, the variable must be assigned a value

int o=11,p=22;
Reftest (ref o, ref P);
Console.WriteLine ("O={0};p ={1}", o,p);
}
}