Special characters
Many metacharacters require special processing when trying to match them. To match these special characters, you must first escape these characters, that is, use a backslash (\). The following table lists the special characters and their meanings:
| Special characters |
Description |
| $ |
Matches the end position of the input string. IfRegExpObjectMultiline$ Also matches '\ n' or' \ R '. To match the $ character, use \ $. |
| () |
Mark the start and end positions of a subexpression. Subexpressions can be obtained for future use. To match these characters, use \ (and \). |
| * |
Matches the previous subexpression zero or multiple times. To match * characters, use \*. |
| + |
Match the previous subexpression once or multiple times. To match + characters, use \ +. |
| . |
Match any single character except linefeed \ n. To match., use \. |
| [ |
Mark the start of a bracket expression. To match [, use \[. |
| ? |
Match the previous subexpression zero or once, or specify a non-Greedy qualifier. To match? Character, use \?. |
| \ |
Mark the next character as a special character, or a literal character, or backward reference, or an octal escape character. For example, 'n' matches the character 'n '. '\ N' matches the line break. The sequence '\' matches "\", while '\ (' matches "(". |
| ^ |
Matches the start position of the input string. Unless used in the square brackets expression, this character set is not accepted. To match the ^ character itself, use \ ^. |
| { |
Mark the start of a qualifier expression. To match {, use \{. |
| | |
Specifies a choice between two items. To match |, use \ |. |