How Can I Check Whether a String Variable Is Empty or Null in C#? [Duplicate]

Since .NET 2.0 you can use:

// Indicates whether the specified string is null or an Empty string.
string.IsNullOrEmpty(string value);

Additionally, since .NET 4.0 there's a new method that goes a bit farther:

// Indicates whether a specified string is null, empty, or consists only of white-space characters.
string.IsNullOrWhiteSpace(string value);

if the variable is a string

bool result = string.IsNullOrEmpty(variableToTest);

if you only have an object which may or may not contain a string then

bool result = string.IsNullOrEmpty(variableToTest as string);

string.IsNullOrEmpty is what you want.

if (string.IsNullOrEmpty(myString)) 
{
  . . .
  . . .
}

Cheap trick:

Convert.ToString((object)stringVar) == ""

This works because Convert.ToString(object) returns an empty string if object is null. Convert.ToString(string) returns null if string is null.

(Or, if you're using .NET 2.0 you could always using String.IsNullOrEmpty.)