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QRegExpValidator Class Reference

The QRegExpValidator class is used to check a string against a regular expression. More...

#include <qvalidator.h>

Inherits QValidator.

List of all member functions.

Public Members

• QRegExpValidator ( QObject * parent, const char * name = 0 )
• QRegExpValidator ( const QRegExp & rx, QObject * parent, const char * name = 0 )
• ~QRegExpValidator ()
• virtual QValidator::State validate ( QString & input, int & pos ) const
• void setRegExp ( const QRegExp & rx )
• const QRegExp & regExp () const

Detailed Description

QRegExpValidator contains a regular expression, "regexp", used to determine whether an input string is Acceptable, Intermediate or Invalid.

The regexp is treated as if it begins with the start of string assertion, ^, and ends with the end of string assertion $ so the match is against the entire input string, or from the given position if a start position greater than zero is given.

For a brief introduction to Qt's regexp engine see QRegExp.

Example of use:

    // regexp: optional '-' followed by between 1 and 3 digits
    QRegExp rx( "-?\\d{1,3}" );
    QValidator* validator = new QRegExpValidator( rx, this );

    QLineEdit* edit = new QLineEdit( this );
    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.

    // integers 1 to 9999
    QRegExp rx( "[1-9]\\d{0,3}" );
    // the validator treats the regexp as "^[1-9]\\d{0,3}$"
    QRegExpValidator v( rx, 0 );
    QString s;

    s = "0";     v.validate( s, 0 );    // returns Invalid
    s = "12345"; v.validate( s, 0 );    // returns Invalid
    s = "1";     v.validate( s, 0 );    // returns Acceptable

    rx.setPattern( "\\S+" );            // one or more non-whitespace characters
    v.setRegExp( rx );
    s = "myfile.txt";  v.validate( s, 0 ); // Returns Acceptable
    s = "my file.txt"; v.validate( s, 0 ); // Returns Invalid

    // A, B or C followed by exactly five digits followed by W, X, Y or Z
    rx.setPattern( "[A-C]\\d{5}[W-Z]" );
    v.setRegExp( rx );
    s = "a12345Z"; v.validate( s, 0 );  // Returns Invalid
    s = "A12345Z"; v.validate( s, 0 );  // Returns Acceptable
    s = "B12";     v.validate( s, 0 );  // Returns Intermediate

    // match most 'readme' files
    rx.setPattern( "read\\S?me(\.(txt|asc|1st))?" );
    rx.setCaseSensitive( FALSE );
    v.setRegExp( rx );
    s = "readme";      v.validate( s, 0 ); // Returns Acceptable
    s = "README.1ST";  v.validate( s, 0 ); // Returns Acceptable
    s = "read me.txt"; v.validate( s, 0 ); // Returns Invalid
    s = "readm";       v.validate( s, 0 ); // Returns Intermediate
    

See also QRegExp, QIntValidator, QDoubleValidator, and Miscellaneous Classes.

Member Function Documentation

QRegExpValidator::QRegExpValidator ( QObject * parent, const char * name = 0 )

QRegExpValidator::QRegExpValidator ( const QRegExp & rx, QObject * parent, const char * name = 0 )

The match is made against the entire string, e.g. if the regexp is [A-Fa-f0-9]+ it will be treated as ^[A-Fa-f0-9]+$.

QRegExpValidator::~QRegExpValidator ()

const QRegExp & QRegExpValidator::regExp () const

Returns the regular expression used for validation.

See also setRegExp().

void QRegExpValidator::setRegExp ( const QRegExp & rx )

See also regExp().

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

The start position is the beginning of the string unless pos is given and is > 0 in which case the regexp is matched from pos until the end of the string.

For example, if the regular expression is \w\d\d (that is, word-character, digit, digit) then "A57" is Acceptable, "E5" is Intermediate and "+9" is Invalid.

See also QRegExp::match() and QRegExp::search().

Reimplemented from QValidator.

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