Var

Var is used to declare the implicitly typed local variable. It finds the type of the variable at compile time.

A Var variable must be initializing at the time of declaration.

Valid var statements:

1.    var str = "1";

2.    var num = 0;

3.    string s = "string";

4.    var s2 = s;

5.    s2 = null;

6.    string s3 = null;

7.    var s4 = s3; 

At compile time, the above var statements are compiled to IL, like this:

1.     string str = "1"; 

2.    int num = 0; 

3.    string s2 = s; 

4.    string s4 = s3;

The compile-time type value of var variable cannot be null but the runtime value can be null.

1.     // invalid var statements 
2.    var v; //need to initialize
3.    var num = null; // can’t be null at compile time 

Once var variable is initialized its data type became fixed to the type of the initial data.

1.     // invalid var statements 
2.    var v2 = "str12";
3.     v2 = 3; // int value can’t be assign to implicitly type string variable v2