C# | IsNullOrWhiteSpace() Method

Last Updated : 31 Jan, 2019

In C#, IsNullOrWhiteSpace() is a string method. It is used to check whether the specified string is null or contains only white-space characters. A string will be null if it has not been assigned a value or has explicitly been assigned a value of null. Syntax:

  public static bool IsNullOrWhiteSpace(String str)

Explanation: This method will take a parameter which is of type System.String and this method will return a boolean value. If the method's parameter list is null or String.Empty, or only contains white-space characters then return True otherwise return False. Example:

  Input : str  = null         // initialize by null value          String.IsNullOrWhiteSpace(str)  Output: True    Input : str  = " "  // initialize by whitespace          String.IsNullOrWhiteSpace(str)  Output: True

Program: To demonstrate the working of the IsNullOrWhiteSpace() Method :

csharp

// C# program to illustrate  // IsNullOrWhiteSpace() Method using System; class Geeks {        // Main Method     public static void Main(string[] args)     {         string s1 = null;          // for null value always return true         bool b1 = String.IsNullOrWhiteSpace(s1);         Console.WriteLine(b1);          string s2 = " ";          // for whitespace value always return true         bool b2 = String.IsNullOrWhiteSpace(s2);         Console.WriteLine(b2);          string s4 = " \n ";          // for new line value return true         bool b4 = String.IsNullOrWhiteSpace(s4);         Console.WriteLine(b4);          string s5 = "\t";          // for tab value return true         bool b5 = String.IsNullOrWhiteSpace(s5);         Console.WriteLine(b5);          string s6 = "\r";          // for carriage Return value return true         bool b6 = String.IsNullOrWhiteSpace(s6);         Console.WriteLine(b6);          string s7 = "GFG";          // for s7 it return False         bool b7 = String.IsNullOrWhiteSpace(s7);         Console.WriteLine(b7);     } }

Output:

  True  True  True  True  True  False

Note: There is a alternative code of IsNullOrWhiteSpace() method as follows:

  return String.IsNullOrEmpty(str) || str.Trim().Length == 0;

Program: To demonstrate IsNullOrEmpty() method’s alternative

CSharp

// C# program to illustrate the  // similar code for IsNullOrWhiteSpace() using System; class Geeks {      // similar code to      // IsNullOrWhiteSpace()     public static bool check(string str)     {         return(String.IsNullOrEmpty(str) ||                str.Trim().Length == 0) ? true : false;     }      // Main Method     public static void Main(string[] args)     {         string s1 = "GeeksforGeeks";         string s2 = " ";          string s3 = null;         string s4 = " \n ";          bool b1 = check(s1);         bool b2 = check(s2);         bool b3 = check(s3);         bool b4 = check(s4);          // To display result         Console.WriteLine(b1);         Console.WriteLine(b2);         Console.WriteLine(b3);         Console.WriteLine(b4);     } }

Output:

  False  True  True  True

Reference: https://msdn.microsoft.com/en-us/library/system.string.isnullorwhitespace

C# | IsNullOrWhiteSpace() Method

Mithun Kumar

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C# | IsNullOrWhiteSpace() Method

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