QLineEdit set min max range?

[whitefurrows]

Hi,

how can i set a Validator to a QLineEdit that accept only values between 1.00 and 16.00 ?

Thanks in advance,

Whitefurrows

[jpn]

QSpinBox (or QDoubleSpinBox) would have the required behaviour, out of the box...

[whitefurrows]

I need a clear input field like a QLineEdit. I can't use a QSpinBox or QDoubleSpinBox because have a button on the right side.

One more tip ?

[jacek]

Then use QDoubleValidator or QRegExpValidator (regexp should be something like "(?:1[0-5]|[1-9])(?:[.,]\\d\\d?)?|16(?:[.,]00?)?").

[whitefurrows]

Hi,

that's great your regexp work fine. I read the doc for QRegExp but i dont know what you do. Can you describe how your regexp work and i understand that. The problem is i have many other ranges to set e.g. 0-50, 15-32, 65-105 and i can't change your regexp.

How can i set a QDoubleValidator its's easey, but my code don't work. I can set values out of range. Why?

lineEdit->setValidator(new QDoubleValidator( 1.00, 16.00, 2, lineEdit));

lineEdit->setValidator(new QDoubleValidator( 1.00, 16.00, 2, lineEdit));

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Greetings,

Whitefurrows

[jacek]

Can you describe how your regexp work and i understand that. The problem is i have many other ranges to set e.g. 0-50, 15-32, 65-105 and i can't change your regexp.

In such case, IMO, it would be better if you create your own validator class, because regexps aren't very readable.

Anyway, suppose you want a regexp for 65-105 range. Valid numbers are:
65, 66, 67, 68, 69, 70, ..., 79, 80, ..., 89, 90, ..., 99, 100, 101, 102, 103, 104, 105

There are three possibilities:

• 6 and one of {5, 6, 7, 8, 9} -> 6[5-9]
• one of {7, 8, 9} and a digit -> [7-9]\\d
• 10 and one of {0, 1, 2, 3, 4, 5} -> 10[0-5]

and you just have to join them: 6[5-9]|[7-9]\\d|10[0-5]

How can i set a QDoubleValidator its's easey, but my code don't work. I can set values out of range. Why?

Because you can enter 1500.00e-2, which is a valid number.

[whitefurrows]

OK i have understand how work the regexp, thank you.

I think really it's better to write my own validator class.

class myDoubleValidator : public QDoubleValidator
{
public:
myDoubleValidator( double bottom, double top, int decimals, QObject* parent = 0)
: QDoubleValidator( bottom, top, decimals, parent){}
 
QValidator::State validate ( QString & input, int &pos ) const
{
if ( input.isEmpty() || input == "." )
return Intermediate;
//I'm not sure what can i do here
return Invalid;
}
 
return Acceptable;
}
};

class myDoubleValidator : public QDoubleValidator
{
public:
myDoubleValidator( double bottom, double top, int decimals, QObject* parent = 0)
: QDoubleValidator( bottom, top, decimals, parent){}

QValidator::State validate ( QString & input, int &pos ) const
{
if ( input.isEmpty() || input == "." )
return Intermediate;
//I'm not sure what can i do here
return Invalid;
}

return Acceptable;
}
};

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Can you help me please?

[jacek]

Take a look at QDoubleValidator::validate() implementation (it's in %QTDIR%/src/gui/widgets/qvalidator.cpp). All you have to do is to remove the part that handles the exponent.

[whitefurrows]

I don't want change orginal files. I try this:

class MyDoubleValidator : public QDoubleValidator
{
public:
	MyDoubleValidator( double bottom, double top, int decimals, QObject* parent = 0)
		: QDoubleValidator( bottom, top, decimals, parent)
	{}
 
	QValidator::State QDoubleValidator::validate(QString & input, int &) const
	{
		QRegExp empty(QString::fromLatin1("-?\\.?"));
		if (input.contains(' '))
			return Invalid;
		if (b >= 0 && input.startsWith(QLatin1Char('-')))
			return Invalid;
		if (empty.exactMatch(input))
			return Intermediate;
		bool ok = true;
		double entered = input.toDouble(&ok);
		int nume = input.count('e', Qt::CaseInsensitive);
		if (!ok) {
			// explicit exponent regexp
			QRegExp expexpexp(QString::fromLatin1("[Ee][+-]?(\\d*)$"));
			int eePos = expexpexp.indexIn(input);
			if (eePos > 0 && nume == 1) {
				QString mantissa = input.left(eePos);
				entered = mantissa.toDouble(&ok);
				if (!ok)
					return Invalid;
				if (expexpexp.cap(1).isEmpty())
					return Intermediate;
			} else if (eePos == 0) {
				return Intermediate;
			} else {
				return Invalid;
			}
		}
 
		int i = input.indexOf('.');
		if (i >= 0 && nume == 0) {
			// has decimal point (but no E), now count digits after that
			i++;
			int j = i;
			while(input[j].isDigit())
				j++;
			if (j - i > d)
				return Intermediate;
		}
 
		if (entered < b || entered > t)
			return Intermediate;
		return Acceptable;
	}
};

class MyDoubleValidator : public QDoubleValidator
{
public:
	MyDoubleValidator( double bottom, double top, int decimals, QObject* parent = 0)
		: QDoubleValidator( bottom, top, decimals, parent)
	{}

	QValidator::State QDoubleValidator::validate(QString & input, int &) const
	{
		QRegExp empty(QString::fromLatin1("-?\\.?"));
		if (input.contains(' '))
			return Invalid;
		if (b >= 0 && input.startsWith(QLatin1Char('-')))
			return Invalid;
		if (empty.exactMatch(input))
			return Intermediate;
		bool ok = true;
		double entered = input.toDouble(&ok);
		int nume = input.count('e', Qt::CaseInsensitive);
		if (!ok) {
			// explicit exponent regexp
			QRegExp expexpexp(QString::fromLatin1("[Ee][+-]?(\\d*)$"));
			int eePos = expexpexp.indexIn(input);
			if (eePos > 0 && nume == 1) {
				QString mantissa = input.left(eePos);
				entered = mantissa.toDouble(&ok);
				if (!ok)
					return Invalid;
				if (expexpexp.cap(1).isEmpty())
					return Intermediate;
			} else if (eePos == 0) {
				return Intermediate;
			} else {
				return Invalid;
			}
		}

		int i = input.indexOf('.');
		if (i >= 0 && nume == 0) {
			// has decimal point (but no E), now count digits after that
			i++;
			int j = i;
			while(input[j].isDigit())
				j++;
			if (j - i > d)
				return Intermediate;
		}

		if (entered < b || entered > t)
			return Intermediate;
		return Acceptable;
	}
};

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but i can't compile!

[jacek]

I try this:

You're on the right track.

It should be:

class MyDoubleValidator : public QDoubleValidator
{
public:
	MyDoubleValidator( double bottom, double top, int decimals, QObject* parent = 0)
		: QDoubleValidator( bottom, top, decimals, parent)
	{}
 
	QValidator::State validate(QString & input, int &) const
	{
		// we don't have the access to private members of QDoubleValidator, 
		// so we must simulate them:
		const double b = bottom();
		const double t = top();
		const int d = decimals();
 
		QRegExp empty(QString::fromLatin1("-?\\.?"));
		if (input.contains(' '))
			return Invalid;
		...
	}
};

class MyDoubleValidator : public QDoubleValidator
{
public:
	MyDoubleValidator( double bottom, double top, int decimals, QObject* parent = 0)
		: QDoubleValidator( bottom, top, decimals, parent)
	{}

	QValidator::State validate(QString & input, int &) const
	{
		// we don't have the access to private members of QDoubleValidator, 
		// so we must simulate them:
		const double b = bottom();
		const double t = top();
		const int d = decimals();

		QRegExp empty(QString::fromLatin1("-?\\.?"));
		if (input.contains(' '))
			return Invalid;
		...
	}
};

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[whitefurrows]

Hi,

that's work fine. Thank you for your great help.

Greetings,

Whitefurrows