PureBasic Forums - English

Posted: **Thu Sep 19, 2013 8:54 pm**

Odd or Even ... that is the question.

Simple procedure to know if a number is odd.

Procedure Odd(Number.l)
  ProcedureReturn Mod(Number,2)  
EndProcedure

Debug Odd(7)
Debug Odd(20)

Posted: **Thu Sep 19, 2013 8:59 pm**

Or (without a function call)

Code: Select all

Procedure Odd(n)
  ProcedureReturn n & 1
EndProcedure

Or (without a procedure call)

Code: Select all

Macro ODD (n)
  (n & 1)
EndMacro

Posted: **Thu Sep 19, 2013 9:52 pm**

luis wrote:Or (no function call)
Code: Select all
Procedure Odd(Number)
  ProcedureReturn Number & 1
EndProcedure

Hi Luis, thanks for teaching me another way to do it.
I checked the time consumed and are identical.
What is the right way?

Code: Select all

Procedure Odd(Number)
  ProcedureReturn Number & 1
EndProcedure
Procedure TOdd(Number.l)
  ProcedureReturn Mod(Number,2)  
EndProcedure


StartTime = ElapsedMilliseconds()
For p=0 To 100000
  TOdd(p)
Next p
ElapsedTime = ElapsedMilliseconds()-StartTime
Debug "minimy: "+StrU(ElapsedTime)

StartTime = ElapsedMilliseconds()            
For p=0 To 100000
  Odd(p)
Next p
ElapsedTime = ElapsedMilliseconds()-StartTime
Debug "Luis: "+StrU(ElapsedTime)

Posted: **Thu Sep 19, 2013 10:06 pm**

You can't accurately check execution time when using the debugger.

cheers

Posted: **Thu Sep 19, 2013 10:12 pm**

There is no right way.

Anyway don't do benchmarks with the debugger enabled, it can skew the results.

Code: Select all

CompilerIf (#PB_Compiler_Debugger = 1)
 CompilerError "Disable Debugger"
CompilerEndIf


Procedure Bitw_Odd(n)
  ProcedureReturn n & 1
EndProcedure

Macro Macro_ODD (n)
  (n & 1)
EndMacro  

Procedure Mod_Odd (n)
  ProcedureReturn Mod(n,2) 
EndProcedure

#times = 500000000

StartTime = ElapsedMilliseconds()
For p=0 To #times
  i = Mod_Odd(p)
Next p
ElapsedTime = ElapsedMilliseconds()-StartTime
MessageRequester("Module: ", StrU(ElapsedTime))

StartTime = ElapsedMilliseconds()           
For p=0 To #times
  i = Bitw_Odd(p)
Next p
ElapsedTime = ElapsedMilliseconds()-StartTime
MessageRequester("bitwise & in proc: ", StrU(ElapsedTime))

StartTime = ElapsedMilliseconds()           
For p=0 To #times
  i = Macro_ODD(p)
Next p
ElapsedTime = ElapsedMilliseconds()-StartTime
MessageRequester("bitwise & in macro :", StrU(ElapsedTime))

Posted: **Thu Sep 19, 2013 10:14 pm**

minimy wrote: What is the right way?

using number & 1 in a macro (instead of a proc) will be the fastest, and most likely a smaller exe size.

Posted: **Thu Sep 19, 2013 10:22 pm**

Well! Many Thanks! every day I learn something new.

Posted: **Fri Sep 20, 2013 4:38 am**

Tenaja wrote:
minimy wrote: What is the right way?
using number & 1 in a macro (instead of a proc) will be the fastest, and most likely a smaller exe size.

The macro is also be limited to only testing integers. The procedure is better if both integers and floats need to be tested because of the automatic type conversion.

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