QValidator(3qt)QValidator(3qt)NAME
QValidator - Validation of input text
SYNOPSIS
#include <qvalidator.h>
Inherits QObject.
Inherited by QIntValidator, QDoubleValidator, and QRegExpValidator.
Public Members
QValidator ( QObject * parent, const char * name = 0 )
~QValidator ()
enum State { Invalid, Intermediate, Valid = Intermediate, Acceptable }
virtual State validate ( QString & input, int & pos ) const = 0
virtual void fixup ( QString & input ) const
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 slippery 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 0 to 999 inclusive, 42 and
123 are Acceptable, the empty string and 1114 are Intermediate and asdf
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 operation 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 Miscellaneous Classes.
Member Type Documentation
QValidator::State
This enum type defines the states in which a validated string can
exist.
QValidator::Invalid - the string is clearly invalid.
QValidator::Intermediate - the string is a plausible intermediate value
during editing.
QValidator::Acceptable - the string is acceptable as a final result,
i.e. it is valid.
MEMBER FUNCTION DOCUMENTATIONQValidator::QValidator ( QObject * parent, const char * name = 0 )
Sets up the validator. The parent and name parameters are passed on to
the QObject constructor.
QValidator::~QValidator ()
Destroys the validator, freeing any storage and other resources used.
void QValidator::fixup ( QString & input ) const [virtual]
This function attempts to change input to be valid according to this
validator's rules. It need not result in a valid string: callers of
this function must re-test afterwards; the default does nothing.
Reimplementations of this function can change input even if they do not
produce a valid string. For example, an ISBN validator might want to
delete every character except digits and "-", even if the result is
still not a valid ISBN; a surname validator might want to remove
whitespace from the start and end of the string, even if the resulting
string is not in the list of accepted surnames.
State QValidator::validate ( QString & input, int & pos ) const [pure virtual]
This pure virtual function returns Invalid if input is invalid
according to this validator's rules, Intermediate if it is likely that
a little more editing will make the input acceptable (e.g. the user
types '4' into a widget which accepts integers between 10 and 99) and
Acceptable if the input is valid.
The function can change input and pos (the cursor position) if it wants
to.
Reimplemented in QIntValidator, QDoubleValidator, and QRegExpValidator.
SEE ALSO
http://doc.trolltech.com/qvalidator.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
license file included in the distribution for a complete license
statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports help us to
help you. Thank you.
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with a
web browser. This man page is provided as a convenience for those users
who prefer man pages, although this format is not officially supported
by Trolltech.
If you find errors in this manual page, please report them to qt-
bugs@trolltech.com. Please include the name of the manual page
(qvalidator.3qt) and the Qt version (3.3.8).
Trolltech AS 2 February 2007 QValidator(3qt)