Difference between string.IsNullOrWhiteSpace and string.IsNullOrEmpty

Most of the times we use string.IsNullOrEmpty and sometimes string.IsNullOrWhiteSpace. The method names itself are self explanatory but to understand them better we will see an example.

String.IsNullOrEmpty:

Function used to check whether string is null or empty.

String.IsNullOrEmpty = (Variable == null || Variable == string.Empty)

String.IsNullOrWhiteSpace:

Function used to check whether a string is null, or contains only of white-space characters, or string.Empty

String.IsNullOrWhiteSpace = (string.IsNullOrEmpty(Variable) || Variable.Trim().Length == 0)

Example:

namespace DotNetMirror
{
    class StringIsNullOrWhiteSpaceAndStringIsNullOrEmpty
    {
        static void Main(string[] args)
        {
            string strVar1 = null;
            string strVar2 = "       ";
            string strVar3 = "    dnm   ";
            string strVar4 = "";
            string strVar5 = "dotnetmirror";

            #region IsNullOrWhiteSpace
            Console.WriteLine("IsNullOrWhiteSpace method");
            Console.WriteLine("String strVar1 {0}", CheckIsNullOrWhiteSpace(strVar1));
            Console.WriteLine("String strVar2 {0}", CheckIsNullOrWhiteSpace(strVar2));
            Console.WriteLine("String strVar3 {0}", CheckIsNullOrWhiteSpace(strVar3));
            Console.WriteLine("String strVar4 {0}", CheckIsNullOrWhiteSpace(strVar4));
            Console.WriteLine("String strVar5 {0}", CheckIsNullOrWhiteSpace(strVar5));
            #endregion
            #region IsNullOrEmpty
            Console.WriteLine("IsNullOrEmpty method");
            Console.WriteLine("String strVar1 {0}", CheckIsNullOrEmpty(strVar1));
            Console.WriteLine("String strVar2 {0}", CheckIsNullOrEmpty(strVar2));
            Console.WriteLine("String strVar3 {0}", CheckIsNullOrEmpty(strVar3));
            Console.WriteLine("String strVar4 {0}", CheckIsNullOrEmpty(strVar4));
            Console.WriteLine("String strVar5 {0}", CheckIsNullOrEmpty(strVar5));
            #endregion

            Console.ReadLine();
        }

        public static string CheckIsNullOrWhiteSpace(string str)
        {
            if (string.IsNullOrWhiteSpace(str))
                return string.Format("[{0}] is Null or Empty or White-space.", str);   
            else
                return string.Format("[{0}] is NOT Null or Empty or White-space.", str);
        }
        public static string CheckIsNullOrEmpty(string str)
        {
            if (string.IsNullOrEmpty(str))
                return string.Format("[{0}] is Null or Empty.", str);   
            else
                return string.Format("[{0}] is NOT Null or Empty.", str);
        }
    }
}

Output:

String.IsNullOrWhiteSpace vs String.IsNullOrEmpty