QRegExp Class Reference

The QRegExp class provides pattern matching using regular expressions or wildcards. More...

#include <qregexp.h>

List of all member functions.

Public Members

QRegExp ()
QRegExp ( const QString &, bool caseSensitive=TRUE, bool wildcard=FALSE )
QRegExp ( const QRegExp & )
~QRegExp ()
QRegExp& operator= ( const QRegExp & )
QRegExp& operator= ( const QString & pattern )
bool operator== ( const QRegExp & ) const
bool operator!= ( const QRegExp & r ) const
bool isEmpty () const
bool isValid () const
bool caseSensitive () const
void setCaseSensitive ( bool )
bool wildcard () const
void setWildcard ( bool )
QString pattern () const
int match ( const QString & str, int index=0, int * len=0, bool indexIsStart = TRUE ) const

Protected Members

void compile ()
const QChar* matchstr ( uint *, const QChar *, uint, const QChar * ) const

Detailed Description

The QRegExp class provides pattern matching using regular expressions or wildcards.

QRegExp knows these regexp primitives:

c matches the character 'c'
. matches any character
^ matches start of input (except [^x] which matches NOT [x])
$ matches end of input
[] matches a set of characters, for example [a-z0-9_]
a* matches a sequence of zero or more a's
a+ matches a sequence of one or more a's
a? matches an optional a
\c escape code for matching special characters like \, [, *, +, . etc.
\b matches the BELL character (7)
\t matches the TAB character (9)
\n matches newline (10)
\r matches return (13)
\s matches white space (defined as any character where QChar::isSpace() returns TRUE. This includes ASCII characters 9 (TAB), 10 (LF), 11 (VT), 12(FF), 13 (CR), and 32 (Space)).
\x12 matches the character 0x12 (18 decimal, 12 hexadecimal).
\022 matches the character 022 (18 decimal, 22 octal).

In wildcard mode, it only knows four primitives:

c matches the character 'c'
? matches any character
* matches any sequence of characters
[] matches a defined set of characters, e.g. [a-zA-Z0-9\.] matches upper and lower case ASCII letters, digits, and dot, and [^z] matches everything except lower-case z.

QRegExp supports Unicode both in the pattern strings and in the strings to be matched.

When writing regular expressions in C++ code, remember that the C++ preprocessor processes \ characters. So in order to match e.g. a "." character, you must write "\\." in C++ source, not "\.".

Bugs and limitations:

Case insensitive matching is not supported for non-ASCII (non-8bit) characters. Any charcter with a non-zero QChar.row() is matched case sensitively even if the QRegExp is in case insensitive mode.

Examples: qmag/qmag.cpp

Member Function Documentation

QRegExp::QRegExp ()

Constructs an empty regular expression.

QRegExp::QRegExp ( const QString & pattern, bool caseSensitive=TRUE, bool wildcard=FALSE )

Constructs a regular expression.

Arguments:

pattern is the regular expression pattern string.
caseSensitive specifies whether or not to use case sensitive matching.
wildcard specifies whether the pattern string should be used for wildcard matching (also called globbing expression), normally used for matching file names.

QRegExp::QRegExp ( const QRegExp & r )

Constructs a regular expression which is a copy of r.

See also: operator=(const and QRegExp&).

QRegExp::~QRegExp ()

Destroys the regular expression and cleans up its internal data.

bool QRegExp::caseSensitive () const

Returns TRUE if case sensitivity is enabled, otherwise FALSE. The default is TRUE.

void QRegExp::compile () `[protected]`

For internal use only.

bool QRegExp::isEmpty () const

Returns TRUE if the regexp is empty.

bool QRegExp::isValid () const

Returns TRUE if the regexp is valid, or FALSE if it is invalid.

The pattern "[a-z" is an example of an invalid pattern, since it lacks a closing bracket.

int QRegExp::match ( const QString & str, int index=0, int * len=0, bool indexIsStart = TRUE ) const

Attempts to match in str, starting from position index. Returns the position of the match, or -1 if there was no match.

If len is not a null pointer, the length of the match is stored in *len.

If indexIsStart is TRUE (the default), the position index in the string will match the start-of-input primitive (^) in the regexp, if present. Otherwise, position 0 in str will match.

Example:

    QRegExp r("[0-9]*\\.[0-9]+");               // matches floating point
    int len;
    r.match("pi = 3.1416", 0, &len);            // returns 5, len == 6

Examples: qmag/qmag.cpp

const QChar * QRegExp::matchstr ( uint * rxd, const QChar * str, uint strlength, const QChar * bol ) const `[protected]`

For internal use only.

bool QRegExp::operator!= ( const QRegExp & r ) const

Returns TRUE if this regexp is not equal to r.

QRegExp & QRegExp::operator= ( const QString & pattern )

Sets the pattern string to pattern and returns a reference to this regexp. The case sensitivity or wildcard options do not change.

QRegExp & QRegExp::operator= ( const QRegExp & r )

Copies the regexp r and returns a reference to this regexp. The case sensitivity and wildcard options are copied, as well.

bool QRegExp::operator== ( const QRegExp & r ) const

Returns TRUE if this regexp is equal to r.

Two regexp objects are equal if they have equal pattern strings, case sensitivity options and wildcard options.

QString QRegExp::pattern () const

Returns the pattern string of the regexp.

void QRegExp::setCaseSensitive ( bool enable )

Enables or disables case sensitive matching.

In case sensitive mode, "a.e" matches "axe" but not "Axe".

void QRegExp::setWildcard ( bool wildcard )

Sets the wildcard option for the regular expression. The default is FALSE.

Setting wildcard to TRUE makes it convenient to match filenames instead of plain text.

For example, "qr*.cpp" matches the string "qregexp.cpp" in wildcard mode, but not "qicpp" (which will be matched in normal mode).

bool QRegExp::wildcard () const

Returns TRUE if wildcard mode is on, otherwise FALSE.