How can I check whether a C# variable is an empty string "" or null?

I am looking for the simplest way to do this check. I have a variable that can be equal to "" or null. Is there a single function that can check if it's not "" or null?

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6 Answers

if (string.IsNullOrEmpty(myString)) { // }
7

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);
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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.)

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