Declaring and initializing a variable

In C#, you should declare a variable before using a variable.

You can declare variable using the following syntax.

Syntax:

{datatype} {variable-name};

Example:

int i;

Assigning a value while declaring is called Initialization.

Syntax:

{datatype} {variable-name} = {expession};

Example:

int i = 100;

Here the expression in the right side is of the type 'int'. So having it in the left side might feel reduntant.

C# has a feature called "Implicitly typed local variables", through which we can avoid this.

Syntax:

var {variable-name} = {expession};

Example:

var i = 100;

This var keyword will work only inside the code block, not at class member level.

If it is at the class member level, C# compiler will through the following error during compilation.

The contextual keyword 'var' may only appear within a local variable declaration or in script code.