Perl's greatest strength is in text and file manipulation, which is accomplished by using the regular expression (regex) library. Regexes, which are quite different from the wildcard handling and filename expansion capabilities of the shell (refer to Chapter 15), allow complicated pattern matching and replacement to be done efficiently and easily. For example, the following line of code replaces every occurrence of the string bob or the string mary with fred in a line of text: $string =~ s/bob|mary/fred/gi; Without going into too many of the details, Table 30.7 explains what the preceding line says.
If you are interested in the details, you can get more information using the regex (7) section of the manual. Although replacing one string with another might seem a rather trivial task, the code required to do the same thing in another language (for example, C) is rather daunting unless supported by additional subroutines from external libraries. |