the index and the number must refer to a location within the string.

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Hello, everyone!

I always have this problem.

public String ReadBarcode(Bitmap img)
{
String imagebarcode = "";
imagebarcode = BarcodeImaging.ReadCode39(img, false, Color.Yellow);
return imagebarcode;
}

with this code I got the Exception:

der Index und die Anzahl müssen sich auf eine Position in der Zeichenfolge beziehen. Parameter:SourceIndex

C#

the index and the number must refer to a location within the string.

How can give me a advice, how to fix this problem.

Posted 8-Dec-15 23:24pm

Member 12075208

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Comments

phil.o 9-Dec-15 5:32am

Please show the line which is throwing the exception; nothing in the code snippet you provided is performing an index-based access to a string.
You can use the stack trace of the exception to know which line :)

Member 12075208 9-Dec-15 8:05am

this line
imagebarcode = BarcodeImaging.ReadCode39(img, false, Color.Yellow);

phil.o 9-Dec-15 8:08am

There is no indexed access to a string in this line. Just an assignation to your variable from the ReadCode39 method.
You should put a breakpoint on this line and execute line-by-line from there to see where the problem appears.

Member 12075208 9-Dec-15 8:19am

I don't have the code of ReadCode39, I just have the Barcodeimaging dll file

phil.o 9-Dec-15 8:24am

Then what is the value of the imagebarcode variable after assignation?
And where else do you use this value? The error message you give does not match the code block you show.

Member 12075208 9-Dec-15 8:28am

yes, I think it comes from ReadCode39, maybe there is string parsing or Substring, then makes this Exception. I just tried to get this value and Console.writeLine.....

phil.o 9-Dec-15 8:33am

Please post the stack trace in your question (not in a comment in a reply to this one).

Member 12075208 9-Dec-15 8:44am

ok , Thank you anyway!

Richard MacCutchan 9-Dec-15 6:38am

The variable SourceIndex contains an invalid value.

Member 12075208 9-Dec-15 8:29am

but i don't know where it comes from.

Richard MacCutchan 9-Dec-15 8:32am

Then you need to use your debugger to step through the code until the line where the error occurs. It is impossible for us to guess what is happening.

Member 12075208 9-Dec-15 8:43am

thank you

Richard MacCutchan 9-Dec-15 8:50am

Had you done that in the first place, and provided all the details it is quite possible you would be close to a solution by now.

Member 12075208 9-Dec-15 9:26am

yes, this is the first time, i use this forum.

Richard MacCutchan 9-Dec-15 9:53am

It's nothing to do with using the forum, more about how you approach problem solving. The first thing to do with any problem is to collect as much useful information as possible. Just showing a few lines of code which do not directly relate to where the error occurs does not give us anything to go on.

Richard MacCutchan 9-Dec-15 6:40am

If you are using the library from this article, then you should post your query in the forum at the end of the article.

Sinisa Hajnal 9-Dec-15 7:01am

I'm guessing ReadCode39 does some parsing and substringing that goes out of range. If you have access to the code, set the breakpoint there and find out when it fails.

Somewhere in your code there is barcode.substring(startPos, readLenght) where one of the parameters falls outside of the barcode string. Either you're sending invalid (or empty) string or there is end char (\0) somewhere in your string. Check reader documentation to see what it appends at the end after read (some readers append "Enter" ascii 13, some specific "end-point" chars...most of them allow this to be configured.

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