StringRegExpReplace char "0x$1"

[AutID]

With what does this pattern replace the captured chars?

Local $sString = "Th%is is %a t%est s%tring"
$sString = StringRegExpReplace ( $sString, "%([0-9a-fA-F]+)", Execute ( Chr ( '0x$1' ) ) )
ConsoleWrite($sString & @LF)

In the example it replaces them with empty string. However this doesn't look too logic to me. If it was the case then the third param of of the reg replace would simply be an empty string.

I found this example on internet.

 

Edited February 23, 2015 by AutID

[SadBunny]

Your code will try to change the regex matches by the result value of the Execute command. Chr ( '0x$1' ) amounts to NUL (ascii char 0), thus the Execute command will try to execute the NUL character. That fails, hence the return value of Execute is "" (as noted in the help file).

If you remove the Execute part but leave the Chr ( '0x$1' ) part, the string will get broken off at the first occurance of the regex match, because the match then still gets replaced by NUL, aka a terminator.

[mikell]

Sometimes in URLs special characters are replaced by a % followed by their hex value (two hex chars), e.g. %20 for the space

Probably this code is made to convert them back to their ascii representation

Local $sString = "Th%20is is %20a t%20est s%20tring"

$sString = StringRegExpReplace ( $sString, "%([0-9a-fA-F]{2})", Execute(Chr('0x$1')) )
ConsoleWrite($sString & @LF)

Edited February 23, 2015 by mikell

[AutID]

I thought the same and it concerns URLs. So in this case they are replaced by and empty string? If yes then why it is like it is and not just an empty string?
 

Edit: like this

Local $sString = "Th%20is is %20a t%20est s%20tring"
$sString = StringRegExpReplace ( $sString, "%([0-9a-fA-F]{2})", "" )
ConsoleWrite($sString & @LF)

  Edited February 25, 2015 by AutID

[mikell]

Because the expression above is bad

The correct way should be this

Local $sString = "Th%20is is %20a t%20est s%20tring"

$sString =  Execute("'" & StringRegexpReplace($sString, "%([0-9a-fA-F]{2})", "'& Chr(0x$1) &'") & "'")
ConsoleWrite($sString & @LF)