Help Understanding StringTrimLeft

[xcaliber13]

Can some get me going in the right direction?   Here is what I am trying to  understand.   I want to find a string ("MSH")  and than delete X amount of characters to the left of that string.   Does StringTrimLeft do that?  Or does StringTrimLeft just deletes characters within the string?  How do I do this?

Any help would be great thank you.    I did search the forums but just didn't find or understand it all.

[czardas]

  On 6/14/2016 at 1:02 PM, xcaliber13 said:

...  and than delete X amount of characters to the left of that string.   Does StringTrimLeft do that?

Expand  

Yes and there is an example in the help file.

Edited June 14, 2016 by czardas

[czardas]

Here's another example:

#include <MsgboxConstants.au3>

Local $sString = "123MHS456"
Local $iPosition = StringInStr($sString, 'MHS')

; delete everything before 'MHS'
$sString = StringTrimLeft($sString, $iPosition -1)

MsgBox($MB_OK, "New String", $sString)

 

[xcaliber13]

czardas,

          Thank you for the reply and the example but here is what I have come up with but it is not working.   Can  you explain why?

#include <file.au3>
#include <FileConstants.au3>

Local $sFile = FileOpen("C:\Temp\Test.txt")
Local $sString = FileRead($sFile)
Local $iPosition = StringInStr($sString, "MSH")

$sString = StringTrimLeft($iPosition, 39)


FileClose($sFile)

Does not remove anything.

[Melba23]

xcaliber13,

You need to specify the string to trim - at the moment you are passing the position of the "MSH" substring, along with some arbitrary value:

$sString = StringTrimLeft($sString, $iPosition)

M23

[nend]

Sound like a job for a regulair expression, this is a small online cours to learn it http://regexone.com/

AutoIt support it totaly.

I've made a program where you can test the regular expression (made in autoit with source code) 

 

Edited June 14, 2016 by nend

[czardas]

Melba has explained this, but here to give you more insight, you need to understand the difference between function return values and parameters. Perhaps the following example will make things a bit clearer. Look again at the help file description - particularly the parameters section and compare it with the code below.

#include <MsgBoxConstants.au3>

$sReturnValue = StringTrimLeft("123MHS456", 3)
MsgBox($MB_OK, "Message Title", $sReturnValue)

Notice that the number of characters trimmed (3 in the example above) is one less than the starting position of the substring "MHS", which starts at the 4th character: look again at the example I posted earlier. Also modify the example in this post and observe the differences to better understand these important points.

Edited June 14, 2016 by czardas