---
name: "qregexpvalidator"
section: "3qt"
platform: "linux"
package: "qt3-doc"
version: "3:3.3.8b-7"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/qregexpvalidator"
---

# qregexpvalidator(3qt)

Used to check a string against a

## NAME

QRegExpValidator - Used to check a string against a

## SYNOPSIS

`#include <qvalidator.h>`

Inherits QValidator.

### 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**\

## DESCRIPTION

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

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;
    int pos = 0;
    s = "0";     v.validate( s, pos );    // returns Invalid
    s = "12345"; v.validate( s, pos );    // returns Invalid
    s = "1";     v.validate( s, pos );    // returns Acceptable
    rx.setPattern( "\\S+" );            // one or more non-whitespace characters
    v.setRegExp( rx );
    s = "myfile.txt";  v.validate( s, pos ); // Returns Acceptable
    s = "my file.txt"; v.validate( s, pos ); // 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, pos );        // Returns Invalid
    s = "A12345Z"; v.validate( s, pos );        // Returns Acceptable
    s = "B12";     v.validate( s, pos );        // 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, pos ); // Returns Acceptable
    s = "README.1ST";  v.validate( s, pos ); // Returns Acceptable
    s = "read me.txt"; v.validate( s, pos ); // Returns Invalid
    s = "readm";       v.validate( s, pos ); // Returns Intermediate
```

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

## MEMBER FUNCTION DOCUMENTATION

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

Constructs a validator that accepts any string (including an empty one) as valid. The object's parent is *parent* and its name is *name*.

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

Constructs a validator which accepts all strings that match the regular expression *rx*. The object's parent is *parent* and its name is *name*.

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 ()

Destroys the validator, freeing any resources allocated.

## const QRegExp & QRegExpValidator::regExp () const

Returns the regular expression used for validation.

See also setRegExp().

## void QRegExpValidator::setRegExp ( const QRegExp & rx )

Sets the regular expression used for validation to *rx*.

See also regExp().

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

Returns Acceptable if *input* is matched by the regular expression for this validator, Intermediate if it has matched partially (i.e. could be a valid match if additional valid characters are added), and Invalid if *input* is not matched.

The *pos* parameter is set to the length of the *input* parameter.

For example, if the regular expression is **&#92;w&#92;d&#92;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.

## SEE ALSO

**http://doc.trolltech.com/qregexpvalidator.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 (qregexpvalidator.3qt) and the Qt version (3.3.8).