perl Pattern Matching
时间：2007-06-25 来源：ilovit
| Modifier | Meaning |
|---|---|
| i | Do case-insensitive pattern matching. |
| m |
Treat string as multiple lines (^ and $ match internal \n). |
| s |
Treat string as single line (^ and $ ignore \n, but . matches \n). |
| x |
Extend your pattern's legibility with whitespace and comments. |
| Assertion | Meaning |
|---|---|
| ^ |
Matches at the beginning of the string (or line, if /m used) |
| $ |
Matches at the end of the string (or line, if /m used) |
| \b |
Matches at word boundary (between \w and \W) |
| \B |
Matches except at word boundary |
| \A |
Matches at the beginning of the string |
| \Z |
Matches at the end of the string |
| \G |
Matches where previous m//g left off |
| (?=...) |
Matches if engine would match ... next |
| (?!...) |
Matches if engine wouldn't match ... next |
| Maximal | Minimal | Allowed Range |
|---|---|---|
| {n,m} | {n,m}? |
Must occur at least n times but no more than m times |
| {n,} | {n,}? |
Must occur at least n times |
| {n} | {n}? |
Must match exactly n times |
| * | *? |
0 or more times (same as {0,}) |
| + | +? |
1 or more times (same as {1,}) |
| ? | ?? |
0 or 1 time (same as {0,1}) |
| Code | Matches |
|---|---|
| \a | Alarm (beep) |
| \n | Newline |
| \r | Carriage return |
| \t | Tab |
| \f | Formfeed |
| \e | Escape |
| \d | A digit, same as [0-9] |
| \D | A nondigit |
| \w | A word character (alphanumeric), same as [a-zA-Z_0-9] |
| \W | A nonword character |
| \s | A whitespace character, same as [ \t\n\r\f] |
| \S | A non-whitespace character |
| Modifier | Meaning |
|---|---|
| g | Match globally, that is, find all occurrences. |
| i | Do case-insensitive pattern matching. |
| m | Treat string as multiple lines. (continued) |
| o | Only compile pattern once. |
| s | Treat string as single line. |
| x | Use extended regular expressions. |
| Modifier | Meaning |
|---|---|
| e | Evaluate the right side as an expression. |
| g | Replace globally, that is, all occurrences. |
| i | Do case-insensitive pattern matching. |
| m | Treat string as multiple lines. |
| o | Only compile pattern once. |
| s | Treat string as single line. |
| x | Use extended regular expressions. |
| Modifier | Meaning |
|---|---|
| c | Complement the SEARCHLIST. |
| d | Delete found but unreplaced characters. |
| s | Squash duplicate replaced characters. |
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