PHP Regular Expressions
Description
Regular expressions provide us with a special syntax for searching for patterns of text within strings.
Syntax
Regular expressions are created by a forward slash /, followed by a sequence of symbols, then another slash and, optionally, a letter.
For example, this simple regular expression searches for the word "world" anywhere within the target string:
/world/Example
The following table shows a list of very basic regular expressions and strings, and whether or not a match is made.
| Function call | Result |
|---|---|
| preg_match("/php/", "php") | True |
| preg_match("php/", "php") | Error; you need a slash at the start |
| preg_match("/php/", "PHP") | False; regexps are case-sensitive |
| preg_match("/php/i", "PHP") | True; /i means "case-insensitive" |
| preg_match("/Foo/i", "FOO") | True |
The i modifier makes regexps case-insensitive.
The preg_match() returns true if there is a match, so you can use it like this:
<?PHP/*w ww. ja v a2s .c o m*/
if (preg_match("/php/i", "PHP")) {
print "Got match!\n";
}
?>
The code above generates the following result.
