yyt_sjq
18th October 2011 07:48 UTC

How to Reverse a String?
  Hi, here

I need to Reverse a String, for example, transfer string to gnirts

How could i manage it? :stare::stare:

thx

LoRd_MuldeR
18th October 2011 10:13 UTC

Use StryCpy in a loop...

Section
        StrCpy $0 "string"  #init
        StrCpy $2 ""        #init
Loop:
        StrCmp $0 "" Done   #done yet?
        StrCpy $1 $0 1 -1   #get last char of $0
        StrCpy $2 "$2$1"    #append last char to $2
        StrCpy $0 $0 -1     #remove last char from $0
        Goto Loop           #loop
Done:
        MessageBox MB_OK "$2"
SectionEnd

MSG
18th October 2011 10:17 UTC

StrLen $0 $YourString
StrCpy $1 ""
loop:
IntOp $0 $0 - 1
${If} $0 == "-1"
goto end
${EndIf}
StrCpy $2 $YourString 1 $0
StrCpy $1 "$1$2"
goto loop
end:

Not tested, but you get the idea.


Edit: Doh, beat me to it. :) Also, funny how our solutions are quite different but the number of OPs is exactly the same. I wonder if an intop is faster than a strcpy?

LoRd_MuldeR
18th October 2011 10:56 UTC

A native C implementation that just swaps s[i] and s[len-i] inplace would probably beat both implementations :)

[EDIT]

Here we go:
http://code.google.com/p/mulder/sour...2FStdUtils.cpp

Lloigor
18th October 2011 11:57 UTC

This is working:

!define StrRev "!insertmacro _StrRev"

>!macro _StrRev _STR_

   Push$1  ;; Reversed string

   Push$2  ;; String Len / Counter

   Push$3  ;; Current character


   StrCpy$1 ""

  StrLen $2 "${_STR_}"


  loop:

  IntCmp $2 0 endloop

      IntOp$2 $2 - 1

      StrCpy$3 "${_STR_}" 1 $2

      StrCpy$1 "$1$3"

      Goto loop

   endloop:


  Pop $3

   Pop$2

   Exch$1

   Pop${_STR_}

!macroend 

>

StrCpy $1 "1234567"

>${StrRev} $1

MessageBox MB_OK "$1" 

"!insertmacro _StrRev"

>!macro _StrRev _STR_

   Push${_STR_}

   Call __StrRev

   Pop${_STR_}

!macroend


>Function __StrRev

   Exch$0  ;; The orig string

   Push$1  ;; Reversed string

   Push$2  ;; String Len / Counter

   Push$3  ;; Current character


   StrCpy$1 ""

  StrLen $2 "$0"


  loop:

  IntCmp $2 0 endloop

      IntOp$2 $2 - 1

      StrCpy$3 "$0" 1 $2

      StrCpy$1 "$1$3"

      Goto loop

   endloop:


  Pop $3

   Pop$2

   Exch$1

   Exch

   Pop$0

FunctionEnd 

>