Perl Matching and substitution
Operatorsm/pattern/gimosxThe “match” operator searches a string for a pattern match. The preceding “m” is usually omitted. The trailing modifiers are as follows
| Modifier | Meaning |
|---|---|
| g | Match globally; find all occurrences |
| i | Do case-insensitive matching |
| m | Treat string as multiple lines |
| o | Only compile pattern once |
| s | Treat string as a single line |
| x | Use extended regular expressions |
s/pattern/replacement/egimosxSearches a string for a pattern, and replaces any match with replacement. The trailing modifiers are all the same as for the match operator, with the exception of “e”, which evaluates the right-hand side as an expression. The substitution operator works on the default variable ($_), unless the =~ operator changes the target to another variable.
tr/pattern1/pattern2/cdsThis operator scans a string and, character by character, replaces any characters matching pattern1 with those from pattern2.
Trailing modifiers are:
| Modifier | Meaning |
|---|---|
| c | Complement pattern1 |
| d | Delete found but unreplaced characters |
| s | Squash duplicated replaced characters |
This can be used to force letters to all uppercase:
tr/a-z/A-Z/;@fields = split(pattern,$input);Split looks for occurrences of a regular expression and breaks the input string at those points. Without any arguments, split breaks on the whitespace in $_:
@words = split;@words = split(/\s+/,$_);$output = join($delimiter,@inlist);Join, the complement of split, takes a list of values and glues them together with the provided delimiting string.