QIntValidator Class

The QIntValidator class provides a validator that ensures a string contains a valid integer within a specified range. More...

Header:	#include <QIntValidator>
CMake:	find_package(Qt6 COMPONENTS Gui REQUIRED) target_link_libraries(mytarget PRIVATE Qt6::Gui)
qmake:	QT += gui
Inherits:	QValidator

• List of all members, including inherited members

Properties

• bottom : int
• top : int

Public Functions

	QIntValidator(int minimum, int maximum, QObject *parent = nullptr)
	QIntValidator(QObject *parent = nullptr)
virtual	~QIntValidator()
int	bottom() const
void	setBottom(int)
void	setRange(int bottom, int top)
void	setTop(int)
int	top() const

Reimplemented Public Functions

virtual void	fixup(QString &input) const override
virtual QValidator::State	validate(QString &input, int &pos) const override

Signals

void	bottomChanged(int bottom)
void	topChanged(int top)

Detailed Description

Example of use:

QValidator *validator = new QIntValidator(100, 999, this);
QLineEdit *edit = new QLineEdit(this);

// the edit lineedit will only accept integers between 100 and 999
edit->setValidator(validator);

Below we present some examples of validators. In practice they would normally be associated with a widget as in the example above.

QString str;
int pos = 0;
QIntValidator v(100, 900, this);

str = "1";
v.validate(str, pos);     // returns Intermediate
str = "012";
v.validate(str, pos);     // returns Intermediate

str = "123";
v.validate(str, pos);     // returns Acceptable
str = "678";
v.validate(str, pos);     // returns Acceptable

str = "999";
v.validate(str, pos);    // returns Intermediate

str = "1234";
v.validate(str, pos);     // returns Invalid
str = "-123";
v.validate(str, pos);     // returns Invalid
str = "abc";
v.validate(str, pos);     // returns Invalid
str = "12cm";
v.validate(str, pos);     // returns Invalid

Notice that the value 999 returns Intermediate. Values consisting of a number of digits equal to or less than the max value are considered intermediate. This is intended because the digit that prevents a number from being in range is not necessarily the last digit typed. This also means that an intermediate number can have leading zeros.

The minimum and maximum values are set in one call with setRange(), or individually with setBottom() and setTop().

QIntValidator uses its locale() to interpret the number. For example, in Arabic locales, QIntValidator will accept Arabic digits.

See also QDoubleValidator, QRegularExpressionValidator, QLocale::toInt(), and Line Edits Example.

Member Function Documentation

QIntValidator::QIntValidator(int minimum, int maximum, QObject *parent = nullptr)

Constructs a validator with a parent, that accepts integers from minimum to maximum inclusive.

QIntValidator::QIntValidator(QObject *parent = nullptr)

Constructs a validator with a parent object that accepts all integers.

[virtual] QIntValidator::~QIntValidator()

Destroys the validator.

[override virtual] void QIntValidator::fixup(QString &input) const

Reimplements: QValidator::fixup(QString &input) const.

void QIntValidator::setRange(int bottom, int top)

Sets the range of the validator to only accept integers between bottom and top inclusive.

[override virtual] QValidator::State QIntValidator::validate(QString &input, int &pos) const

Reimplements: QValidator::validate(QString &input, int &pos) const.

Returns Acceptable if the input is an integer within the valid range. If input has at most as many digits as the top of the range, or is a prefix of an integer in the valid range, returns Intermediate. Otherwise, returns Invalid.

If the valid range consists of just positive integers (e.g., 32 to 100) and input is a negative integer, then Invalid is returned. (On the other hand, if the range consists of negative integers (e.g., -100 to -32) and input is a positive integer, then Intermediate is returned, because the user might be just about to type the minus (especially for right-to-left languages).

Similarly, if the valid range is between 46 and 53, then 41 and 59 will be evaluated as Intermediate, as otherwise the user wouldn't be able to change a value from 49 to 51.

int pos = 0;

s = "abc";
v.validate(s, pos);    // returns Invalid

s = "5";
v.validate(s, pos);    // returns Intermediate

s = "50";
v.validate(s, pos);    // returns Acceptable

By default, the pos parameter is not used by this validator.