string IsNullOrEmpty string vs string IsNullOrWhiteSpace string

Question

Is use of string IsNullOrEmpty string  when checking a string considered as bad practice when there is string IsNullOrWhiteSpace string  in  NET 4 0 and above

User · Answer

They are different functions  You should decide for your situation what do you need   I don t consider using any of them as a bad practice  Most of the time IsNullOrEmpty   is enough  But you have the choice

User · Answer

Here is the actual implementation of both methods   decompiled using dotPeek    TargetedPatchingOptOut  Performance critical to inline across NGen image boundaries        public static bool IsNullOrEmpty string value              if  value    null          return value Length    0        else         return true                  lt summary gt          Indicates whether a specified string is null  empty  or consists only of white-space characters           lt  summary gt                    lt returns gt          true if the  lt paramref name  value   gt  parameter is null or  lt see cref  F System String Empty   gt   or if  lt paramref name  value   gt  consists exclusively of white-space characters           lt  returns gt           lt param name  value  gt The string to test  lt  param gt      public static bool IsNullOrWhiteSpace string value              if  value    null          return true        for  int index   0  index  lt  value Length    index                  if   char IsWhiteSpace value index              return false                return true

User · Answer

The differences in practice    string testString       Console WriteLine string Format  IsNullOrEmpty    0    string IsNullOrEmpty testString     Console WriteLine string Format  IsNullOrWhiteSpace    0    string IsNullOrWhiteSpace testString     Console ReadKey     Result   IsNullOrEmpty   True IsNullOrWhiteSpace   True                                                                 string testString     MDS       IsNullOrEmpty   False IsNullOrWhiteSpace   False                                                                 string testString           IsNullOrEmpty   False IsNullOrWhiteSpace   True                                                                 string testString   string Empty   IsNullOrEmpty   True IsNullOrWhiteSpace   True                                                                 string testString   null   IsNullOrEmpty   True IsNullOrWhiteSpace   True

User · Answer

What about this for a catch all     if  string IsNullOrEmpty x Trim          This will trim all the spaces if they are there avoiding the performance penalty of IsWhiteSpace  which will enable the string to meet the  empty  condition if its not null   I also think this is clearer and its generally good practise to trim strings anyway especially if you are putting them into a database or something

User · Answer

In the  Net standard 2 0      string IsNullOrEmpty    Indicates whether the specified string is null or an Empty string    Console WriteLine string IsNullOrEmpty null                 True Console WriteLine string IsNullOrEmpty                      True Console WriteLine string IsNullOrEmpty                      False Console WriteLine string IsNullOrEmpty                      False      string IsNullOrWhiteSpace    Indicates whether a specified string is null  empty  or consists only of white-space characters    Console WriteLine string IsNullOrWhiteSpace null           True Console WriteLine string IsNullOrWhiteSpace                True Console WriteLine string IsNullOrWhiteSpace                True Console WriteLine string IsNullOrWhiteSpace                True

User · Answer

The best practice is selecting the most appropriate one       Net Framework 4 0 Beta 2 has a new IsNullOrWhiteSpace   method for   strings which generalizes the IsNullOrEmpty   method to also include other white   space besides empty string       The term    white space    includes all characters that are not visible on   screen  For example  space  line break  tab and empty string are white   space characters      Reference   Here     For performance  IsNullOrWhiteSpace is not ideal but is   good  The method calls will result in a small performance penalty    Further  the IsWhiteSpace method itself has some indirections that can   be removed if you are not using Unicode data  As always  premature   optimization may be evil  but it is also fun    Reference   Here  Check the source code  Reference Source  NET Framework 4 6 2   IsNullorEmpty    Pure  public static bool IsNullOrEmpty String value        return  value    null    value Length    0       IsNullOrWhiteSpace   Pure  public static bool IsNullOrWhiteSpace String value        if  value    null  return true       for int i   0  i  lt  value Length  i              if  Char IsWhiteSpace value i    return false             return true      Examples  string nullString   null  string emptyString       string whitespaceString           string nonEmptyString    abc123    bool result   result   String IsNullOrEmpty nullString                 true result   String IsNullOrEmpty emptyString                true result   String IsNullOrEmpty whitespaceString           false result   String IsNullOrEmpty nonEmptyString             false  result   String IsNullOrWhiteSpace nullString            true result   String IsNullOrWhiteSpace emptyString           true result   String IsNullOrWhiteSpace whitespaceString      true result   String IsNullOrWhiteSpace nonEmptyString        false

User · Answer

Check this out with IsNullOrEmpty and IsNullOrwhiteSpace  string sTestes    I like sweat peaches       Stopwatch stopWatch   new Stopwatch        stopWatch Start        for  int i   0  i  lt  5000000  i                  for  int z   0  z  lt  500  z                          var x   string IsNullOrEmpty sTestes     OR string IsNullOrWhiteSpace                      stopWatch Stop           Get the elapsed time as a TimeSpan value      TimeSpan ts   stopWatch Elapsed         Format and display the TimeSpan value       string elapsedTime   String Format   0 00   1 00   2 00   3 00            ts Hours  ts Minutes  ts Seconds          ts Milliseconds   10       Console WriteLine  RunTime     elapsedTime       Console ReadLine      You ll see that IsNullOrWhiteSpace is much slower

User · Answer

It says it all IsNullOrEmpty   does not include white spacing while IsNullOrWhiteSpace   does   IsNullOrEmpty   If string is  -Null -Empty  IsNullOrWhiteSpace   If string is  -Null -Empty -Contains White Spaces Only

User · Answer

string IsNullOrEmpty str  - if you d like to check string value has been provided  string IsNullOrWhiteSpace str  - basically this is already a sort of business logic implementation  i e  why      is bad  but something like      is good    My advice - do not mix business logic with technical checks  So  for example  string IsNullOrEmpty is the best to use at the beginning of methods to check their input parameters

[c#] string.IsNullOrEmpty(string) vs. string.IsNullOrWhiteSpace(string)

Examples related to c#

Examples related to .net

Examples related to string