C# | IsNullOrEmpty() Method
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).
Syntax:
public static bool IsNullOrEmpty(String str)
Explanation: This method will take a parameter which is of type System.String and this method will returns a boolean value. If the str parameter is null or an empty string (“”) then return True otherwise return False.
Example:
Input : str = null // initialize by null value String.IsNullOrEmpty(str) Output: True Input : str = String.Empty // initialize by empty value String.IsNullOrEmpty(str) Output: True
Program: To demonstrate the working of the IsNullOrEmpty() Method :
// C# program to illustrate // IsNullOrEmpty() Method using System; class Geeks { // Main Method public static void Main( string [] args) { string s1 = "GeeksforGeeks" ; // or declare String s2.Empty; string s2 = "" ; string s3 = null ; // for String value Geeks, return true bool b1 = string .IsNullOrEmpty(s1); // For String value Empty or "", return true bool b2 = string .IsNullOrEmpty(s2); // For String value null, return true bool b3 = string .IsNullOrEmpty(s3); Console.WriteLine(b1); Console.WriteLine(b2); Console.WriteLine(b3); } } |
False True True
Note: IsNullOrEmpty method enables to check whether a String is null or its value is Empty and its alternative code can be as follows:
return s == null || s == String.Empty;
Program: To demonstrate IsNullOrEmpty() method’s alternative
// C# program to illustrate the // similar method for IsNullOrEmpty() using System; class Geeks { // to make similar method as IsNullOrEmpty public static bool check( string s) { return (s == null || s == String.Empty) ? true : false ; } // Main Method public static void Main( string [] args) { string s1 = "GeeksforGeeks" ; // or declare String s2.Empty; string s2 = "" ; string s3 = null ; bool b1 = check(s1); bool b2 = check(s2); bool b3 = check(s3); // same output as above program Console.WriteLine(b1); Console.WriteLine(b2); Console.WriteLine(b3); } } |
False True True
Reference: https://msdn.microsoft.com/en-us/library/system.string.isnullorempty(v=vs.110).aspx