How can I check a C# variable is an empty string “” or null? [duplicate]

Answer 1

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

Answer 2

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

Answer 3

string.IsNullOrEmpty is what you want.

Answer 4

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.)

Answer 5

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);

Answer 6

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);