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Testing for Empty String

, 21 Feb 2008 CPOL
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A brief comparison of techniques of testing for empty strings

Background

Every once in a while, someone will post a snippet with code such as...

if ( somestring == "" )

... and in many cases someone else will respond, "Always use if ( somestring.Length == 0 ), it's more efficient."

... or maybe someone will respond, "Always use if ( somestring == System.String.Empty ), it's more efficient."

And neither will back up his claim.

Here are some numbers; performing each test against a provided string (UInt32.MaxValue times) yields:

C:\>StrTest ""
00:01:09.3764731 // if ( providedstring == "" )
00:01:10.3869118 // if ( providedstring == localstaticemptystring )
00:01:10.1249723 // if ( providedstring == System.String.Empty )
00:00:38.1334581 // if ( providedstring.Length == 0 )

C:\>StrTest "abc"
00:01:36.3041617 // if ( providedstring == "" )
00:01:36.6285272 // if ( providedstring == localstaticemptystring )
00:01:35.9541459 // if ( providedstring == System.String.Empty )
00:00:31.6860051 // if ( providedstring.Length == 0 )

The difference between comparing against a literal empty string and a static empty string is negligible. And note that somehow when the provided string isn't empty, those tests take even longer!

Testing the Length of the string is the clear winner here, though it's not as Earth-shattering as some might have you believe.

History

  • 2008-02-21 First submitted

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

PIEBALDconsult
Software Developer (Senior)
United States United States
BSCS 1992 Wentworth Institute of Technology
 
Originally from the Boston (MA) area. Lived in SoCal for a while. Now in the Phoenix (AZ) area.
 
OpenVMS enthusiast, ISO 8601 evangelist, photographer, opinionated SOB
 
---------------
 
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"linq'ish" sounds like "inept" in German -- Andreas Gieriet
 
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"Omit needless local variables." -- Strunk... had he taught programming
 

 
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My first rule of debugging: "If you get a different error message, you're making progress."
 
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My general rule of software development: "Design should be top-down, but implementation should be bottom-up."

Comments and Discussions

 
GeneralHmm PinmemberZeroDegrez22-Feb-08 5:48 
GeneralRe: Hmm PinmemberPIEBALDconsult22-Feb-08 7:48 
QuestionHave you tested these? PinmemberCCMint21-Feb-08 17:44 
AnswerRe: Have you tested these? PinmemberPIEBALDconsult22-Feb-08 7:41 
GeneralSo it is not me only... PinmemberOleg Shilo21-Feb-08 16:35 
GeneralRe: So it is not me only... PinmemberPIEBALDconsult22-Feb-08 7:40 
GeneralRe: So it is not me only... PinmemberOleg Shilo24-Feb-08 11:06 
GeneralRe: So it is not me only... PinmemberThomas Weller29-Nov-08 18:44 
GeneralRe: So it is not me only... PinmemberPIEBALDconsult30-Nov-08 5:57 
GeneralRe: So it is not me only... PinmemberOleg Shilo30-Nov-08 12:10 
GeneralRe: So it is not me only... PinmemberThomas Weller30-Nov-08 23:34 
GeneralRe: So it is not me only... PinmemberPIEBALDconsult1-Dec-08 11:08 
GeneralRe: So it is not me only... Pinmembermm52850430-Jan-09 3:53 
GeneralRe: So it is not me only... PinmemberPIEBALDconsult30-Jan-09 5:22 
GeneralRe: So it is not me only... Pinmembermm52850431-Jan-09 9:05 
GeneralRe: So it is not me only... PinmemberPIEBALDconsult31-Jan-09 9:18 
GeneralRe: So it is not me only... Pinmembermm5285041-Feb-09 6:14 

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