QLineEdit doubleValidator starting with point

Question

I have a UI with a QLineEdit which only accepts float/double values with the help of a QDoubleValidator. It only accepts values if I enter a leading number like: 0.234. But I'd prefer to be able to enter values directly without a leading number like .234. Unfortunately the QDoubleValidator does not accept a leading point. Is there any way to archive my goal with the help of the validator, or do I have to check every entered character myself? I'm using Qt 5.9.1 on Windows10.

QDoubleValidator* doubleValidator = new QDoubleValidator();
QLineEdit* lineEdit = new QLineEdit(frame);
lineEdit->setValidator(doubleValidator);
vbox->addWidget(lineEdit);

What version of qt are you using? This works fine for me (with or without a leading dot) when using either qt-4.8.7 or qt-5.10.0. Please provide a [mcve]. — ekhumoro, Dec 26 '17 at 19:46
Sorry, it is the first time I post something, will read the link, thanks. — haggi krey, Dec 27 '17 at 11:39

score 0 · Accepted Answer · answered Dec 26 '17 at 18:55

0

Unfortunately, QDoubleValidator is pretty limited, but you can use QRegExpValidator to get what you want with a regex describing a number, depending on the notation you expect.

// non-scientific floating-point numbers
QRegExp rx("[-+]?[0-9]*\\.?[0-9]+");
QRegExpValidator v(rx, 0);
QString s;
s = ".123";
v.validate(s, 0);    // Returns Acceptable

This is much more extendable, and allows you to abstract it to any condition, with basic regular expression knowledge.

answered Dec 26 '17 at 18:55

Alex Huszagh

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Did you actually test `QDoubleValidator`? It works fine for me. – ekhumoro Dec 26 '17 at 19:49
Yes, I checked the QDoubleValidator and it does not accept a leading ".", at least on my machine here. – haggi krey Dec 27 '17 at 11:46
What is your version of Qt and OS? – eyllanesc Dec 27 '17 at 11:54
1

Qt 5.9.1 on Windows10. – haggi krey Dec 27 '17 at 11:56
1

Tried QDoubleValidator on Ubuntu 14.04 with qt4.8.7 and it also works fine for me. – user270049 Dec 27 '17 at 12:40
Thanks for testing, so it seems to be a Window only problem, maybe others can approve it? – haggi krey Dec 28 '17 at 18:21
@haggikrey I just got around to testing it, and it works here. My guess would be a locale problem then, since the double validation is tightly tied to the locale. – Alex Huszagh Dec 28 '17 at 19:01

QLineEdit doubleValidator starting with point

1 Answers1