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QValidator Class Reference

Inheritance diagram for QValidator:

QObject QDoubleValidator QIntValidator QRegExpValidator

List of all members.

Detailed Description

The QValidator class provides validation of input text.

The class itself is abstract. Two subclasses, QIntValidator and QDoubleValidator, provide basic numeric-range checking, and QRegExpValidator provides general checking using a custom regular expression.

If the built-in validators aren't sufficient, you can subclass QValidator. The class has two virtual functions: validate() and fixup().

validate() must be implemented by every subclass. It returns Invalid, Intermediate or Acceptable depending on whether its argument is valid (for the subclass's definition of valid).

These three states require some explanation. An Invalid string is clearly invalid. Intermediate is less obvious: the concept of validity is difficult to apply when the string is incomplete (still being edited). QValidator defines Intermediate as the property of a string that is neither clearly invalid nor acceptable as a final result. Acceptable means that the string is acceptable as a final result. One might say that any string that is a plausible intermediate state during entry of an Acceptable string is Intermediate.

Here are some examples:

For a line edit that accepts integers from 10 to 999 inclusive, 42 and 123 are Acceptable, the empty string and 5 are Intermediate, and "asdf" and 1114 is Invalid.

For an editable combobox that accepts URLs, any well-formed URL is Acceptable, "http://www.trolltech.com/," is Intermediate (it might be a cut and paste action that accidentally took in a comma at the end), the empty string is Intermediate (the user might select and delete all of the text in preparation for entering a new URL) and "http:///./" is Invalid.

For a spin box that accepts lengths, "11cm" and "1in" are Acceptable, "11" and the empty string are Intermediate, and "http://www.trolltech.com" and "hour" are Invalid.

fixup() is provided for validators that can repair some user errors. The default implementation does nothing. QLineEdit, for example, will call fixup() if the user presses Enter (or Return) and the content is not currently valid. This allows the fixup() function the opportunity of performing some magic to make an Invalid string Acceptable.

QValidator is typically used with QLineEdit, QSpinBox and QComboBox.

See also:
QIntValidator, QDoubleValidator, QRegExpValidator, {Line Edits Example}

Definition at line 37 of file qvalidator.h.

Public Types

enum  State { Invalid, Intermediate, Acceptable }

Public Slots

void deleteLater ()


void destroyed (QObject *=0)

Public Member Functions

bool blockSignals (bool b)
const QObjectListchildren () const
bool connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool disconnect (const QObject *receiver, const char *member=0)
bool disconnect (const char *signal=0, const QObject *receiver=0, const char *member=0)
void dumpObjectInfo ()
void dumpObjectTree ()
QList< QByteArraydynamicPropertyNames () const
virtual bool event (QEvent *)
virtual bool eventFilter (QObject *, QEvent *)
template<typename T>
findChild (const QString &name=QString()) const
template<typename T>
QList< T > findChildren (const QRegExp &re) const
template<typename T>
QList< T > findChildren (const QString &name=QString()) const
virtual void fixup (QString &) const
bool inherits (const char *classname) const
void installEventFilter (QObject *)
bool isWidgetType () const
void killTimer (int id)
void moveToThread (QThread *thread)
QString objectName () const
QObjectparent () const
QVariant property (const char *name) const
 QValidator (QObject *parent)
void removeEventFilter (QObject *)
void setObjectName (const QString &name)
void setParent (QObject *)
bool setProperty (const char *name, const QVariant &value)
void setUserData (uint id, QObjectUserData *data)
bool signalsBlocked () const
int startTimer (int interval)
QThreadthread () const
QObjectUserData * userData (uint id) const
virtual State validate (QString &, int &) const =0
 ~QValidator ()

Static Public Member Functions

static bool connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
static bool disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
static uint registerUserData ()

Protected Member Functions

virtual void childEvent (QChildEvent *)
virtual void connectNotify (const char *signal)
virtual void customEvent (QEvent *)
virtual void disconnectNotify (const char *signal)
int receivers (const char *signal) const
QObjectsender () const
virtual void timerEvent (QTimerEvent *)

Protected Attributes

QObjectData * d_ptr

Static Protected Attributes

static const QMetaObject staticQtMetaObject


QString objectName
 the name of this object


class QApplication
class QApplicationPrivate
class QCoreApplication
class QCoreApplicationPrivate
struct QMetaObject
class QThreadData
class QWidget

Related Functions

(Note that these are not member functions.)

qFindChild (const QObject *obj, const QString &name=QString(), T dummy=0)
qFindChild (const QObject *obj, const QString &name)
QList< T > qFindChildren (const QObject *obj, const QString &name=QString(), T dummy=0)
QList< T > qFindChildren (const QObject *obj, const QRegExp &regExp)
QList< T > qFindChildren (const QObject *obj, const QString &name)
T * qobject_cast (QObject *object)
void * qt_find_obj_child (QObject *parent, const char *type, const QString &name)

The documentation for this class was generated from the following files:

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