C / C++ / MFC

Re: How to extract all words - using regular expression

26-Oct-23 22:16

The following will find all words:

/\w+/g

You can test it quite quickly at RegExr: Learn, Build, & Test RegEx[^].

But it would help if you showed us the actual text you are working with, and the results you get.

And please use <pre> tags around the code parts so your question is clear.

Salvatore Terress27-Oct-23 10:21

Re: How to extract all words - using regular expression

27-Oct-23 10:21

Many thanks for all the support.

FYI
I did use "[ -~]+" to extract first continuous words. Now I am working on to extract ALL words...

I did try pass "[/\w+/g]+" to my otherwise working function and ended up with [/w+/g]+
- the back slash is missing,

And this is result , part of my debug messages

" instring text  \t\n Waiting to connect to bluetoothd..."
" regular expression \t\n  [/w+/g]+"
" Has all match g"

You asked for the string I am trying to extract stuff from

here it is

"Waiting to connect to bluetoothd...\r\u001B[0;94m[bluetooth]\u001B[0m#                                                                              \r\r\u001B[0;94m[bluetooth]\u001B[0m# \r                        \rAgent registered\n\u001B[0;94m[bluetooth]\u001B[0m# "

As you can see - the extracted "g" is from "Agent". No good...

I suspect Qt is messing with passing the backslash...

C++

        // result = BTUL->EditLine_RegExp_Ext(result, "[ -~]+",textEditPtr_DEBUG, textEditPtr_DEBUG);
       result = BTUL->EditLine_RegExp_Ext(result, "[/\w+/g]+",textEditPtr_DEBUG, textEditPtr_DEBUG);

<pre lang="C++">

"Waiting to connect to bluetoothd..."
"Waiting to connect to bluetoothd..."
"START EditLine_RegExp...QString BT_Utility_Library::EditLine_RegExp_Ext(QString, QString, QTextEdit *, QTextEdit *)1321"
" instring text  \t\n Waiting to connect to bluetoothd..."
" regular expression \t\n  [/w+/g]+"
" Has all match g"

Richard MacCutchan27-Oct-23 22:13

Re: How to extract all words - using regular expression

27-Oct-23 22:13

The backslash character is used as the escape character within strings, so you need to escape it:

"[/\\w+/g]+"

jschell27-Oct-23 10:11

jschell

27-Oct-23 10:11

Salvatore Terress wrote:
Where is my error ??

Your question is not specific to regular expressions but also to what is running the regular expression engine. But you did not provide that information.

A 'g' is something that is external to regular expressions. So where you are using it is important and the only clue you provided is 'EditLine_RegExp' which googling for returned no results. But certainly since you didn't escape the backslash for the g that would never work.

Other than that of course there is also the following
- A space is not considered a word. Your capture group includes that.
- There could be more than one space.
- Are you matching on a single line? If not there are other complications.
- If there is ONLY words in your line then it is pointless to use regex at all. Just split it.
- If there are OTHER things besides words then I don't believe what you are doing will work (but again you didn't state what so maybe it is.)

Re: How to extract all words - using regular expression

Salvatore Terress27-Oct-23 14:01

Re: How to extract all words - using regular expression

27-Oct-23 14:01

Your question is not specific to regular expressions but also to what is running the regular expression engine. But you did not provide that information.

Since most of "AI reg expressions" generators are working and Qt SAME expression does not - you have a point.

I guess I will ask in Qt forum about that.

Yes, there are other means to verify that the string contains desired word, (QString "contains" method works peachy )
however, I sure like to learn more about using regular expression - so I like to stick with reg expressions for now.

ADDENDUM
My post is about using regular expression - it is NOT about the function I am using to actually implement regular expression. That function works as expected and there is no need to evacuate that function here.
If it did not work as desired I would say so.

Salvatore Terress28-Oct-23 5:21

Re: How to extract all words - using regular expression

28-Oct-23 5:21

Here is the actual snippet of the code.
I have "hard coded " the RegExp

C++

     // "[/\\w+/g]+"
        RegExp = "[/\\w+/g]+";
        text = " validate regular expression   ";
        text += RegExp;
        qDebug() << text;
        textDEBUG->append(text);

        // RegExp = "[/\\w+/g]+";
        text = " validate inString   ";
        text += inString;
        qDebug() << text;
        textDEBUG->append(text);


        QRegularExpression re(RegExp);


        // QRegularExpression re("/([A-Z])\w+/g");
//QRegularExpression re("([A-Z])\w+");

        QRegularExpressionMatch match = re.match(inString);

        if (match.hasMatch()) { // matches all
            text = " Has all match ";
            QStringList result = match.capturedTexts();

            text += result.at(0);    // test show only first

            qDebug() << text;
            textDEBUG->append(text);

            return result.at(0);

Here is the relevant debug output

"START EditLine_RegExp...QString BT_Utility_Library::EditLine_RegExp_Ext(QString, QString, QTextEdit *, QTextEdit *)1321"
" instring text  \t\n Waiting to connect to bluetoothd...\r\u001B[0;94m[bluetooth]\u001B[0m#                                                                              \r\r\u001B[0;94m[bluetooth]\u001B[0m# \r                        \rAgent registered\n\u001B[0;94m[bluetooth]\u001B[0m# "
" regular expression \t\n  (\\w+\\s:?)"
" validate regular expression   [/\\w+/g]+"
" validate inString   Waiting to connect to bluetoothd...\r\u001B[0;94m[bluetooth]\u001B[0m#                                                                              \r\r\u001B[0;94m[bluetooth]\u001B[0m# \r                        \rAgent registered\n\u001B[0;94m[bluetooth]\u001B[0m# "
" Has all match Waiting"
10:12:17: /mnt/RAID_124/BT/BT_Oct23_BASE_/mdi/MDI exited with code 0

The expression matches ONLY the first word it finds.
My goal is to match ALL the words in the inString.

I am going to try one of the AI reg exp generators, but from experience
using them this RegExp MAY work....

k505428-Oct-23 6:27

k5054

28-Oct-23 6:27

Maybe this SO page can help you? https://stackoverflow.com/questions/37003623/how-to-capture-multiple-repeated-groups

Keep Calm and Carry On

Re: How to extract all words - using regular expression

jschell30-Oct-23 5:23

jschell

30-Oct-23 5:23

Salvatore Terress wrote:
learn more about using regular expression....RegExp = "[/\\w+/g]+";

Keep in mind that that form of a regular expression will be unlikely to work in any other regular expression interpreter.

Perl, javascript, C# and Java (perhaps others) all use the same rules for most of the basics for regex and that will not work with any of them.

For those that means the following
- Match A-Za-z0-9.
- Match a forward slash (redundant twice)
- Match a 'g'. Redundant with the word class match.

Re: How to extract all words - using regular expression

Salvatore Terress29-Oct-23 4:48

called pointer is null...

29-Oct-23 4:48

After some "RTFM" I came up with this code

C++

if(inString.contains("Agent") & inString.contains("registered") )
       {
           text = "Match ";
       }else
       {
           text = " No match ";
       }


       qDebug() << text;
       textDEBUG->append(text);

The " contains " actually accepts reg expression and string too , so I am not sure how
to tell the difference.
But it does what I want it to do.

Salvatore Terress24-Oct-23 6:50

24-Oct-23 6:50

SOLVED

Thanks to all contributors who help to find the issue.

modified 29-Oct-23 10:49am.

k505424-Oct-23 7:01

k5054

24-Oct-23 7:01

At a guess, I would bet that textEditPtr_DEBUG may not be a valid object. In brief:

C++

QTextEdit *textEditPtr_DEBUG = MWCCF->centralWidget()->findChild<QTextEdit *>("textEdit_2");
if (textEditPtr_DEBUG) {
   // textEditPtr_DEBUG is valid here
} else {
   // textEditPtr_DEBUG is not valid here
   // and we don't do anything to create a valid object ...
}
// At this point, if the else branch was followed, above then do not
// have a valid textEditPtr_DEBUG object  ...
textEditPtr_DEBUG->append(text);  //crashes as noted above

Keep Calm and Carry On

Dave Kreskowiak24-Oct-23 7:10

Dave Kreskowiak

24-Oct-23 7:10

Well, it's pretty obvious this call:

C++

QTextEdit *textEditPtr_DEBUG = MWCCF->centralWidget()->findChild<QTextEdit *>("textEdit_2");

didn't find and return the object you thought it did.

Whatever "textEdit_2" is either doesn't exist or it's not in the container you think it is and are telling the code it's in.

I know you're saying "OK here", but is it really? Put a breakpoint on the if statement right above that and run the code under the debugger. When it breaks, hover the mouse over textEditptr_DEBUG and see if it actually has a value that isn't a bunch of zeros and points to the actual object you think it does.

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.
Dave Kreskowiak

Message Closed

24-Oct-23 8:15

24-Oct-23 8:15

Message Closed

modified 26-Oct-23 12:36pm.

Dave Kreskowiak24-Oct-23 9:00

Dave Kreskowiak

24-Oct-23 9:00

Hell if I know. I haven't C++'d in about 15 years and I don't do Qt.

The process of checking return values for exactly what you expect them to be is just universal.

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.
Dave Kreskowiak

Richard MacCutchan24-Oct-23 22:12

24-Oct-23 22:12

The code, and the problem, is quite clear.

C++

  1  QTextEdit *textEditPtr_DEBUG = MWCCF->centralWidget()->findChild<QTextEdit *>("textEdit_2");
  2  if (textEditPtr_DEBUG)
  3  {
  4      text = " Found textEdit ";   OK here
  5      qDebug() << text;
  6      textEditPtr_DEBUG->append(text);
  7  
  8      text = " DEBUG START  DEBUG trace with textEdit_2" ;
  9      qDebug() << text;
 10      textEditPtr_DEBUG->append(text);
 11  }
 12  else
 13  {
 14      text = "Did not find any QTextEdit";
 15      qDebug() << text;
 16  }
 17  // ?? what why ??
 18  text = " DEBUG START  DEBUG trace with textEdit_2" ;
 19  textEditPtr_DEBUG->append(text);     crash -  null pointer here ??

At line 1 you (try to) create a pointer to some object.
At line 2 you test if that object is NULL, and if it is not, then you execute lines 4 to 10
If the object is NULL, then you skip to line 14
But then at line 19 you try to use a pointer which you may already have determined is NULL.

Unfortunately the debug output you have shown above does not match that code, so I am making some assumptions here.

[edit]
Also it does not help you to have the same debug message in two different places.
[/edit]

modified 25-Oct-23 5:13am.

CPallini24-Oct-23 22:38

CPallini

24-Oct-23 22:38

Pretty good assumptions, I believe.

"In testa che avete, Signor di Ceprano?"
-- Rigoletto

jschell25-Oct-23 4:44

jschell

25-Oct-23 4:44

Richard MacCutchan wrote:
If the object is NULL, then you skip to line 14

The OP shows the posted output. For example the following line.

" Sucess Found textEdit "

So line 5 is being executed (and the other lines in that block by the rest of the output.)

Of course the code is still wrong if the null pointer does show up.

Richard MacCutchan wrote:
the debug output you have shown above does not match that code

Perhaps that is the actual problem. They think they are running the code shown but the code being executed is different. I have had that happen to me. Often enough that I probably do compiles, cleans and builds far more often than is needed.

Richard MacCutchan25-Oct-23 4:50

Regular expression error ?

25-Oct-23 4:50

jschell wrote:
Perhaps that is the actual problem. They think they are running the code shown but the code being executed is different.

Given who I suspect is asking the question I am not at all surprised.

And if you look at OP's reply to Dave Kreskowiak you will see more confusion.

Salvatore Terress21-Oct-23 7:42

Re: Regular expression error ?

21-Oct-23 7:42

I am trying to extract MAC address from text, and it is failing.

Here is the debug print of the "inString" text to extract the MAC from :

"Inquiring ...\n\t98:D3:31:F8:39:33\tclock offset: 0x7c6b\tclass: 0x001f00\n"

Here is my temporary code with regular expression which must be in error, but I do not see it.

QRegularExpression re(" [^\x00-\x7F]+\\ *(?:[^\x00-\x7F]| )*");
        QRegularExpressionMatch match = re.match(inString);


         if (match.hasMatch()) {
            text = " Has match ";
            QStringList result = match.capturedTexts();
            text += result.at(0);    // test show only first

         }
         else
         {
            text = " NO match found ";
         }

 qDebug() << text;

Here is "run time error " , I am not sure why " invalid object" .

Does it mean my regular expression is incorrect ?

QRegularExpressionPrivate::doMatch(): called on an invalid QRegularExpression object
" NO match found "

If additional info would help, please ask.

Help analyzing the expression would be also greatly appreciated.

Thanks

Richard Andrew x6421-Oct-23 7:50

Richard Andrew x64

21-Oct-23 7:50

You can validate your regex at any number of sites that do that sort of thing. That would help you determine if the problem is the regex itself, or the QRegularExpression object.

The difficult we do right away...
...the impossible takes slightly longer.

Re: Regular expression error ?

Richard Andrew x6421-Oct-23 8:12

Richard Andrew x64

21-Oct-23 8:12

I can see one thing wrong with the expression right off the bat.

You're trying to match hexadecimal characters from 00 to FF, but the range you specify is only 00 to 7F.

The difficult we do right away...
...the impossible takes slightly longer.

Re: Regular expression error ?

Salvatore Terress21-Oct-23 8:58