CE101

StringManagement .... Bug in StringReplace() ????

9 posts in this topic

 

I've just discovered that in StringReplace() -- if the SearchString is null, then the returned value will also be null.

The format is:     StringReplace ( "string", "searchstring/start", "replacestring" [, occurrence = 0 [, casesense = 0]] )

Here's an example:

$var1 = "ABCDEFG"
$var2 = ""
$var3 = "X"

$var1 = StringReplace($var1, $var2, $var3)

$Msg    =        "var1 = "        & $var1     &  @CRLF
$Msg    = $Msg & "@error = "      & @error    &  @CRLF
$Msg    = $Msg & "@extended = "   & @error

MsgBox($MB_SYSTEMMODAL, "", $Msg)

The result will be:    $var = null, @error = 1, @extended = 1

According to the documentation @extended says how many replacements were made.
But it does not mention anything about @error.

Is this a bug -- or a special feature?

 

 

 

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Maybe a little buggy with empty strings as this shows 0 replacements.  I also believe it is returning an empty string (not NULL) and setting the error to 1 as the behavior for any/all errors.

$var1 = "ABCDEFG"
$var2 = "AB"
$var3 = ""

$var1 = StringReplace($var1, $var2, $var3)

$Msg    =        "var1 = "        & $var1     &  @CRLF
$Msg    = $Msg & "@error = "      & @error    &  @CRLF
$Msg    = $Msg & "@extended = "   & @error

MsgBox(0, "", $Msg)

 

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,-. .--. ________ .-. .-. ,---. ,-. .-. .-. .-.
|(| / /\ \ |\ /| |__ __||| | | || .-' | |/ / \ \_/ )/
(_) / /__\ \ |(\ / | )| | | `-' | | `-. | | / __ \ (_)
| | | __ | (_)\/ | (_) | | .-. | | .-' | | \ |__| ) (
| | | | |)| | \ / | | | | | |)| | `--. | |) \ | |
`-' |_| (_) | |\/| | `-' /( (_)/( __.' |((_)-' /(_|
'-' '-' (__) (__) (_) (__)

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10 hours ago, CE101 said:

The result will be:    $var = null, @error = 1, @extended = 1

This is the result of your bugy script (c&p). When corrected output is:

Quote

var1 =
@error = 1
@extended = 0

 

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Thank you all for getting back to me.

Iamtheky writes:
> Maybe a little buggy with empty strings as this shows 0 replacements.  
> I also believe it is returning an empty string (not NULL) and setting the error to 1 as the behavior for any/all errors.

Are there two separate things??  An "empty" variable and a variable containing a "null" value (asci(0)).
The following script shows they are the same.

$var2 = Chr(0)
        $var3 = ""
        $var4 = ""

        If $var2 = $var3   Then
            $var4 = "They are equal"
        Else
            $var4 = "They are not equal"
        Endif

        $var5 = ASC($var2)
        $var6 = ASC($var3)
        $Msg =        "ASCI($var2) = "        & $var5   &  @CRLF
        $Msg = $Msg & "ASCI($var3) = "        & $var6   &  @CRLF
        $Msg = $Msg & $var4
        MsgBox($MB_SYSTEMMODAL, "", $Msg)

 

Andy writes:
> seems to be a never ending story...
> https://www.autoitscript.com/trac/autoit/ticket/2666

Thank you. Very interesting. However I don’t see anything in that post specific to my issue.
 

AutoBert writes:
> This is the result of your bugy script (c&p). When corrected output is:
> var1 =
> @error = 1
> @extended = 0  


Thank you. Yes my mistake (copy/pasting) regarding @extended.
Instead of:             $Msg    = $Msg & "@extended = "   & @error
It should read:       $Msg    = $Msg & "@extended = "   & @extended

CASE1
    $var1 = "ABCDEFG"
    $var2 = ""
    $var3 = "X"
    $var1 = StringReplace($var1, $var2, $var3)
The result will be:    $var1 = null, @error = 1, @extended = 0

Questions:  
(1) Since there were no replacements (@extended = 0) why is $var1 changed to Null.
(2) Why would there be a replacement? $var2 is not found in $var1.
(3) The fact that the documentation makes no mention of @error makes me wonder.
(4) I wonder if any other String functions handle null values poorly like this.
(5) Do you think I should report this as a bug? It would be a simple fix. At the beginning of the function check Parameter2 (the SearchString). If it is null -- Then Return.

 

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#6 ·  Posted (edited)

35 minutes ago, CE101 said:

Are there two separate things??

Dont know, I was more attempting to convey that i believe it only behaves as stated in the help file, it just does so for more cases.

 

Helpfile should read:

"However, if there are not enough characters in "string" for the entire "replacestring" to be inserted, *or any other stupid stuff with the strings*, an empty string is returned and @error is set to 1."

Edited by iamtheky
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,-. .--. ________ .-. .-. ,---. ,-. .-. .-. .-.
|(| / /\ \ |\ /| |__ __||| | | || .-' | |/ / \ \_/ )/
(_) / /__\ \ |(\ / | )| | | `-' | | `-. | | / __ \ (_)
| | | __ | (_)\/ | (_) | | .-. | | .-' | | \ |__| ) (
| | | | |)| | \ / | | | | | |)| | `--. | |) \ | |
`-' |_| (_) | |\/| | `-' /( (_)/( __.' |((_)-' /(_|
'-' '-' (__) (__) (_) (__)

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9 hours ago, CE101 said:

Are there two separate things??  An "empty" variable and a variable containing a "null" value (asci(0)).

An empty string (variable of type String having length = 0) is a completely distinct beast from a variable containing the keyword Null (see help file). Null is to be understood as "I don't know", i.e. denotes that a variable has no defined type and hence no defined value. From this point of view it's the same concept as Null in SQL, despite Null in AutoIt does convert differently from SQL in expressions.

A string containing the ASCII velue NULL is = Chr(0x00) so it's a string of length 1 containing the ASCII character Chr(0x00) aka NULL. Again a completely distinct thing.

 

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Thank you all for the clarifications.

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