How come this doesnt work?

[ShaChris23]

I wrote some code that tries to extract an integer 100 out of this string:

"AB,SH#100 \r\n\0"

but the toInt() always fails; i.e. 0 is returned from toInt(). Note that the original data came in from QByteArray(). I currently use append() to convert from QByteArray to QString.

As a separate question, is there a better way to convert QByteArray to QString than QString::append()?




QByteArray bte = "AB,SH#100 \r\n\0";
QString test;
test.append( bte );
QStringList list = test.split( "," );
QStringList tmp = list.filter( "SH#" );

tmp[0].remove( 0, 3 );
int value = test.toInt();


Thanks!

[wysota]

If you remove the three characters from the beginning, you still have the whitespaces and 0 at the end, so toInt() will fail.

[high_flyer]

Why not just use QRegExp?

[ShaChris23]

can somebody post the solution in code?

[wysota]

What is exactly that you want? You have to describe a general case and not a single example string.

[ShaChris23]

[Quote]
I wrote some code that tries to extract an integer 100 out of this string:

"AB,SH#100 \r\n\0"
[/quoute]

That's exactly what I want. Just try extracting it. Note to wyota: toInt() doesnt fail even if you have 100 spaces after SH#100

[wysota]

I wrote some code that tries to extract an integer 100 out of this string:

"AB,SH#100 \r\n\0"


That's exactly what I want. Just try extracting it.[/QUOTE]


QString func(const QString &s){ return "100"; }
I doubt that's what you want...

If you don't tell us what are the rules of extraction in general way, we can't possibly give you code (other than I have given above) to do it. You said "extract 100", so return "100" seems a fine way to do it.

[ShaChris23]

Hi,

Thanks for all the inputs. How about this:

A string contains many fields. Each field starts with a 2 ASCII characters followed by the # sign.

Each field is delimited by a comma.

The last field is terminated by "\r\n"

We need to extract the number ( int or float ) after the # sign.

e.g. "DV#1200.03,AB#34,SH#100\r\n\0"

So for example, if a user is interested in the field "SH", he has to

Extract the SH field out,
Chop off first 3 characters
Convert the remaining string to be a number.

I hope this is helpful. I might be wrong here...but I think there's a bug in the Qt's QstringList::filter() method.

Thanks!

[wysota]

I'd do:

float extractCmd(const QString &str, const QString &expected){
if(expected.size()>2 || str.size()<4) return 0;
QStringList commands = str.simplified().split(",");
static QRegExp rx("([A-Z][A-Z])#([0-9]*\\.?[0-9]+)");
foreach(QString cmd, commands){
if(!rx.exactMatch(cmd))
continue;
if(rx.cap(1)==expected)
return rx.cap(2).toFloat();
}
}

QString str = "DV#1200.03,AB#34,SH#100\r\n\0";
float val = extractCmd(str, "SH");