User Guide

Regular expression syntax 301

Note that only the \n character signals the end of a line. The following characters do not:

■ Return (\r) character

■ Unicode line-separator (\u2028) character

■ Unicode paragraph-separator (\u2029) character

The s (dotall) flag

If the s (dotall or “dot all”) flag is not set, a dot (.) in a regular expression pattern does not

match a newline character (

\n). So for the following example, there is no match:

var str:String = "Test\n";

str += "Multiline";

var re:RegExp = /.*?<\/p>/;

trace(str.match(re));

However, if the s flag is set, the dot matches the newline character:

var str:String = "Test\n";

str += "Multiline";

var re:RegExp = /.*?<\/p>/s;

trace(str.match(re));

In this case, the match is the entire substring within the tags, including the newline

character:

Test

Multiline

The x (extended) flag

Regular expressions can be difficult to read, especially when they include a lot of metasymbols

and metasequences. For example:

/<p(>|(\s*[^>]*>)).*?<\/p>/gi

When you use the x (extended) flag in a regular expression, any blank spaces that you type in

the pattern are ignored. For example, the following regular expression is identical to the

previous example:

/ | (\s* [^>]* >)) .*? <\/p> /gix

If you have the x flag set and do want to match a blank space character, precede the blank

space with a backslash. For example, the following two regular expressions are equivalent:

/foo bar/

/foo \ bar/x