C # implicit type

Implicit type

(1) Origin

Before an implicit type occurs,

When we declare a variable,

Always specify its type for a variable

Even when foreach is a set,

You must also specify the variable type for the elements of the traversal set.

Implicit type,

Programmers don't have to do this anymore.

(2) Usage

Let's look at the following code:

Var a = 1; // int a = 1; var B = "123"; // string B = "123"; var myObj = new MyObj (); // MyObj myObj = new MyObj ()

The above lines of code play the same role as the comments behind each line of code.

That is to say, when declaring a variable (and assigning values to it at the same time), you do not need to specify the type of the variable. As long as a var is used, the problem is solved.

(3) Are you worried that such writing will reduce performance?

I can tell you responsibly that this write will not affect performance!

The above code and the code in the comments are exactly the same after the compiled IL code (intermediate language code)

(The IL code generated by the compiler based on the variable value and the type of the variable)

(4) benefits of this keyword:

You do not need to write the variable type twice when declaring a variable and assigning values to the variable.

(This really saves developers a lot of time)

When foreach is a set, you can use the var keyword to replace the type of the circular variable.

(5) Considerations

You cannot declare a variable with the var keyword without assigning a value to it.

The compiler cannot export the type of your variable.