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From: aotto1968 <aotto1968@t-online.de>
Newsgroups: comp.lang.tcl
Subject: Re: good to know: tcl static "regexp" is faster than tcl "string"
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Date: Tue, 31 Dec 2024 19:33:41 +0100
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....
> 
> But neither is quite as fast as string match (athough regex is close):
> 
> $ cat time-check.tcl
> #!/usr/bin/env tclsh
> 
> proc test-1 { val } {
>    if {[regexp ^:: $val]} {
>      return true
>    } else {
>      return false
>    }
> }
> 
> proc test-2 { val } {
>    if {[string range $val 0 1] eq "::"} {
>      return true
>    } else {
>      return false
>    }
> }
> 
> proc test-3 { val } {
>    return [string match ::* $val]
> }
> 
> set num 100000
> puts 1=[time {test-1 ::otto} $num]
> puts 2=[time {test-1 otto}   $num]
> puts 3=[time {test-2 ::otto} $num]
> puts 4=[time {test-2 otto}   $num]
> puts 5=[time {test-3 ::otto} $num]
> puts 6=[time {test-3 otto}   $num]
> 
> $ ./time-check.tcl
> 1=0.45252 microseconds per iteration
> 2=0.42354 microseconds per iteration
> 3=0.58949 microseconds per iteration
> 4=0.58363 microseconds per iteration
> 5=0.4351 microseconds per iteration
> 6=0.41378 microseconds per iteration

interesting

1) tcl with debug on

[debug].../NHI1> ./sbin/tcl-time-check.tcl
1=1.07665 microseconds per iteration
2=1.04722 microseconds per iteration
3=1.34974 microseconds per iteration
4=1.34743 microseconds per iteration
5=1.07671 microseconds per iteration
6=1.04552 microseconds per iteration

2) tcl with "production" switch on

[release].../NHI1> ./sbin/tcl-time-check.tcl
1=0.32721 microseconds per iteration
2=0.31452 microseconds per iteration
3=0.4352 microseconds per iteration
4=0.43953 microseconds per iteration
5=0.32741 microseconds per iteration
6=0.31617 microseconds per iteration

there is NO difference between "regexp" and "string match" for

→ Intel(R) Xeon(R) CPU E3-1275 V2 @ 3.50GHz