What is 'long?' data type?

I am going over some code written by another developer and am not sure what long? means:

protected string AccountToLogin(long? id) { string loginName = ""; if (id.HasValue) { try {.... 

6 Answers

long is the same as Int64

long data type

The ? means it is nullable

A nullable type can represent the normal range of values for its underlying value type, plus an additional null value

Nullable Types

Nullable example:

int? num = null; if (num.HasValue == true) { System.Console.WriteLine("num = " + num.Value); } else { System.Console.WriteLine("num = Null"); } 

This allows you to actually check for a null value instead of trying to assign an arbitrary value to something to check to see if something failed.

I actually wrote a blog post about this here.

long is an Int64, the ? makes it nullable.

"long?" is a nullable 64-bit signed integer. It's equivalent to Nullable<Int64>.

long? is a 64-bit, nullable integer.

To clarify, nullable means it can be null or an integer number ( 0, 1, etc.).

long? is a nullable type. This means that the id parameter can have a long value or be set to null. Have a look at the HasValue and Value properties of this parameter.

It's a nullable type declaration.