QDoubleValidator accepts multiple decimal points

Question

I'm using a QDoubleValidator for my QLineEdit. The application locale (set in QtCreator) is QLocale::German.

Now when I enter a valid double (either using a dot or a comma as decimal separator) writing to the textedit as well as converting the string to a float works perfectly fine. But the validator also lets me write stuff with multiple decimal separators. Strings like 123.567,890 or ,,03.4... get validated but can't get converted into a float.

Is there a way to tell QDoubleValidator to only validate real numbers and not just strings without alphabetical characters?

I basically want to have a validator, that only validates strings, that can get converted to floats using either the default locale or the german locale.

Why don't you use a [`QDoubleSpinBox`](http://doc.qt.io/qt-5/qdoublespinbox.html) ? It will automatically use the system locale, and you can [hide the up/down buttons](http://doc.qt.io/qt-5/qabstractspinbox.html#buttonSymbols-prop) if you don't want to see them. — p.i.g., May 26 '15 at 19:06

Bowdzone · Accepted Answer · 2014-10-30T12:47:40.733

4

I have not used the QDoubleValidator so far but I could achieve such behaviour by using a QRegExpValidator:

QRegExpValidator* rxv = new QRegExpValidator(QRegExp("[+-]?\\d*[\\.,]?\\d+"), this);
lineedit->setValidator(rxv);

edited Oct 30 '14 at 12:47

answered Oct 30 '14 at 12:07

Bowdzone

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Does not work: When there already is text in the lineedit, I can type whatever I want. When the lineedit is empty, I can't type anything. :/ – Uroc327 Oct 30 '14 at 12:27
May you mean `\\d[\\.,]?` instead of `\\d\\[.,]?`? – Uroc327 Oct 30 '14 at 12:31
You are right of course, thanks for the notice. I edit the answer – Bowdzone Oct 30 '14 at 12:47

score 2 · Answer 2 · answered Oct 30 '14 at 12:09

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If you want only convert your content into the float and you don't want locale specifications, you can use QRegExpValidator with next deep regexp.

ui->lineEdit->setValidator(new QRegExpValidator(QRegExp("[-+]?[0-9]*\\.?[0-9]+([eE][-+]?[0-9]+)?")));

answered Oct 30 '14 at 12:09

Jablonski

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my solution: QRegExpValidator *validate = new QRegExpValidator(QRegExp("[0-9]*([\\.,]?[0-9]{0,2})?")); – blackmoon Dec 15 '17 at 16:06

QDoubleValidator accepts multiple decimal points

2 Answers2