在switch（）闭包内定义变量

Question

Is it possible in C# to define a variable like so?

switch(var num = getSomeNum()) {
   case 1: //Do something with num
           break;

   default: break;
}

public static int GetSomeNum() => 3;

Answer 1

The documentation says that

In C# 6, the match expression must be an expression that returns a value of the following types:

• a char.

• a string.

• a bool.

• an integral value, such as an int or a long.

• an enum value.

Starting with C# 7, the match expression can be any non-null expression.

To answer your question,

Yes you can switch on an int, eg

int myInt = 3;
switch(myInt)

Yes you can switch on the result of a method that returns an it, eg

int GetMyInt() 
{
    // Get my Int
}

switch(GetMyInt())

Yes you can switch on variable populated with a method result, eg

int GetMyInt() 
{
    // Get my Int
}

int myInt = GetMyInt();

switch(myInt)

No you can't do it like that.