QRegExp Class Reference
The QRegExp class provides pattern matching using regular expressions or wildcards.
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#include <qregexp.h>
List of all member functions.
Public Members
Protected Members
void compile () (internal)
const QChar* matchstr ( uint *, const QChar *, uint, const QChar * ) const (internal)
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
- $ matches end of input
- [] matches a defined set of characters - see below.
- 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 such
as \, [, *, +, . etc.
- \t matches the TAB character (9)
- \n matches newline (10)
- \r matches return (13)
- \s matches a white space (defined as any character
for which QChar::isSpace() returns TRUE. This includes at least
ASCII characters 9 (TAB), 10 (LF), 11 (VT), 12(FF), 13 (CR) and 32
(Space)).
- \d matches a digit (defined as any character for
which QChar::isDigit() returns TRUE. This includes at least ASCII
characters '0'-'9').
- \x1f6b matches the character with unicode point U1f6b
(hexadecimal 1f6b). \x0012 will match the ASCII/Latin1 character
0x12 (18 decimal, 12 hexadecimal).
- \022 matches the ASCII/Latin1 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 - see below.
QRegExp supports Unicode both in the pattern strings and in the
strings to be matched.
When writing regular expressions in C++ code, remember that C++
processes \ characters. So in order to match e.g. a "." character,
you must write "\\." in C++ source, not "\.".
A character set matches a defined set of characters. For example,
[BSD] matches any of 'B', 'D' and 'S'. Within a character set, the
special characters '.', '*', '?', '^', '$', '+' and '[' lose their
special meanings. The following special characters apply:
- ^ When placed first in the list, changes the
character set to match any character not in the list. To include
the character '^' itself in the set, escape it or place it anywhere
but first.
- - Defines a range of characters. To include the
character '-' itself in the set, escape it or place it last.
- ] Ends the character set definition. To include the
character ']' itself in the set, escape it or place it first (but
after the negation operator '^', if present)
Thus, [a-zA-Z0-9.] matches upper and lower case ASCII letters,
digits and dot; and [^\s] matches everything except white space.
\note In Qt 3.0, the language of regular expressions will contain
five more special characters, namely '(', ')', '{', '|' and '}'. To
ease porting, it's a good idea to escape these characters with a
backslash in all the regular expressions you'll write from now on.
Bugs and limitations:
- Case insensitive matching is not supported for non-ASCII/Latin1
(non-8bit) characters. Any character 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.
See also setWildcard().
QRegExp::QRegExp ( const QRegExp & r )
Constructs a regular expression which is a copy of r.
See also operator=(const and QRegExp&).
QRegExp::~QRegExp ()
Destructs 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.
See also setCaseSensitive().
int QRegExp::find ( const QString & str, int index )
Attempts to match in str, starting from position index.
Returns the position of the match, or -1 if there was no match.
See also match().
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
\note In Qt 3.0, this function will be replaced by find().
Examples:
qmag/qmag.cpp
bool QRegExp::operator!= ( const QRegExp & r ) const
Returns TRUE if this regexp is not equal to r.
See also operator==().
QRegExp & QRegExp::operator= ( const QString & pattern )
This function is obsolete. It is provided to keep old source working, and will probably be removed in a future version of Qt. We strongly advise against using it in new code.
Consider using setPattern() instead of this method.
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".
See also: caseSensitive().
void QRegExp::setPattern ( 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.
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 would be matched in normal mode).
See also wildcard().
bool QRegExp::wildcard () const
Returns TRUE if wildcard mode is on, otherwise FALSE.
See also setWildcard().
void QRegExp::compile () [protected]
For internal use only.
const QChar * QRegExp::matchstr ( uint * rxd, const QChar * str, uint strlength, const QChar * bol ) const [protected]
For internal use only.
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