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C# String IsNullOrEmpty() Method

Last Updated : 25 Mar, 2025
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In C#, IsNullOrEmpty() is a string method. It is used to check whether the specified string is null or an Empty string. A string will be null if it has not been assigned a value. A string will be empty if it is assigned “” or String.Empty (A constant for empty strings).

Example 1: Using IsNullOrEmpty() to check whether the string is Null or empty.

C# 
// C# program to demonstrate the use of  
// String.IsNullOrEmpty() method  
using System;  
class Geeks  
{  
    static void Main(string[] args)  
    {   
        // Empty String  
        string s1 = "";  

        // Non-Empty String  
        string s2 = "Geek";  

        // Check for null or empty string  
        bool res = String.IsNullOrEmpty(s1);  

        // Display the result  
        Console.WriteLine($"\"{s1}\" is null or empty: {res}");  
        res = String.IsNullOrEmpty(s2);  

        // Display the result  
        Console.WriteLine($"\"{s2}\" is null or empty: {res}");  
    }  
}

Output
"" is null or empty: True
"Geek" is null or empty: False

Syntax:

public static bool IsNullOrEmpty(String str)

  • Parameter: It takes a single parameter str, which is of type System.String
  • Return-Type: Returns a boolean value. If the str parameter is null or an empty string (“”) then return True otherwise return False.

Note: The IsNullOrEmpty method is used to check whether a string is either null or empty ("").
A simple alternative to IsNullOrEmpty() can be written as:

return s == null || s == String.Empty;

This alternative works similarly but lacks the built-in optimization and clarity of IsNullOrEmpty().

Example 2: Demonstrating a similar method to IsNullOrEmpty() and its internal workings.

C# 
// C# program to illustrate an  
// alternative method for IsNullOrEmpty()  
using System;  
class Geeks  
{  
    // Custom method similar to IsNullOrEmpty()  
    public static bool Check(string s)  
    {  
        return s == null || s == String.Empty; // Equivalent to IsNullOrEmpty()  
    }  

    // Main Method  
    public static void Main(string[] args)  
    {  
        string s1 = "GeeksforGeeks";  

        // Declare an empty string  
        string s2 = "";  

        // Declare a null string  
        string s3 = null;  

        bool b1 = Check(s1);  
        bool b2 = Check(s2);  
        bool b3 = Check(s3);  

        // Display the result  
        Console.WriteLine(b1);  
        Console.WriteLine(b2);  
        Console.WriteLine(b3);  
    }  
}

Output
False
True
True

M
Mithun Kumar
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