Searches subject for
matches to pattern and
replaces them with
replacement. If
limit is specified, then only
limit matches will be replaced; if limit is omitted or is -1, then all
matches are replaced.
Replacement may
contain references of the form \\n or (since PHP 4.0.4)
$n, with the latter form being the preferred
one. Every such reference will be replaced by the text
captured by the n'th
parenthesized pattern. n
can be from 0 to 99, and \\0 or $0 refers to the text matched by the
whole pattern. Opening parentheses are counted from left to
right (starting from 1) to obtain the number of the capturing
subpattern.
注: When working with a replacement pattern where a backreference is immediately followed by another number (i.e.: placing a literal number immediately after a matched pattern), you cannot use the familiar \\1 notation for your backreference. \\11, for example, would confuse preg_replace() since it does not know whether you want the \\1 backreference followed by a literal 1, or the \\11 backreference followed by nothing. In this case the solution is to use \${1}1. This creates an isolated $1 backreference, leaving the 1 as a literal.
If matches are found, the new
subject will be returned, otherwise subject will be returned
unchanged.
Every parameter to
preg_replace() (except
limit) can be an array.
注: When using arrays with pattern and replacement, the keys are processed in the order they appear in the array. This is not necessarily the same as the numerical index order. If you use indexes to identify which pattern should be replaced by which replacement, you should perform a ksort() on each array prior to calling preg_replace().
If subject is an
array, then the search and replace is performed on every
entry of subject, and the
return value is an array as well.
If pattern and replacement are arrays, then preg_replace() takes a value from each
array and uses them to do search and replace on subject. If
replacement has fewer values than pattern, then empty string is used
for the rest of replacement values. If
pattern is an array and
replacement is a string, then this replacement
string is used for every value of
pattern. The converse would not make sense,
though.
/e modifier makes preg_replace() treat the replacement parameter as PHP code
after the appropriate references substitution is done. Tip:
make sure that replacement
constitutes a valid PHP code string, otherwise PHP will
complain about a parse error at the line containing preg_replace().
$startDate = 5/27/1999 |
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注: Parameter limit was added after PHP 4.0.1pl2.
See also preg_match(),
preg_match_all(), and
preg_split().