The var keyword in C # describes the _c# tutorial in detail

C # var keyword detailed

var is the 3.5 new type that defines a variable in fact, that is, the definition of a weakening type Var can replace any type of compiler that will judge you by context. What kind of case would you like to use Var? I think you're not sure what type you're going to use. var is similar Object but more efficient than object.

Or in layman's terms:

var can be understood as an anonymous type, and we can think of it as a placeholder for declaring a variable. It is used primarily when declaring a variable and cannot determine the data type.

The following four features are used to define variables using var:

1. Must be initialized at the time of definition. That is, it must be var s = "ABCD" form, not the following form: Var s; s = "ABCD";

2. Once the initialization is complete, the variable can no longer be assigned a different value than the initialization value type.

3. The var requirement is a local variable.

4. By using the var definition variable and object, it is exactly the same in terms of efficiency and the use of a strongly typed method to define variables.

Instance:

Using System;
Using System.Collections.Generic;
Using System.Linq;
Using System.Text;
Using System.Threading.Tasks;

Namespace Firstpriject
{
  class program
  {
    static void Main (string[] args)
    {
      //Declaration and initialization of variables
      var name = "John";
      var age = ten;
      var sex = true;

      Gets the variable's data type type
      T_name = Name. GetType ();
      Type T_age = age. GetType ();
      Type t_sex = Sex. GetType ();

      Print result
      Console.WriteLine (the type of variable Name is {0}, the type of variable age is {1}, the type of variable sex is {2} ",
        t_name.tostring (), t_age.tostring (), t_sex.tostring ());

      Do not automatically close the console, waiting for input
      console.readline ();}}

Example result diagram:

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