Sams Teach Yourself Perl in 21 Days, Second Edition

Increment and Decrement Operators

The ++ and -- operators are used with a variable to increment or decrement that variable by 1 (that is, to add or subtract 1). And as with C, both operators can be used either in prefix fashion (before the variable, ++$x) or in postfix (after the variable, $x++). Depending on the usage, the variable will be incremented or decremented before or after it's used.

If your reaction to the previous paragraph is “Huh?”, here's a wordier explanation. The ++ and -- operators are used with scalar variables to increment or decrement the value of that variable by 1, sort of an even shorter shorthand to the += or -= operators. In addition, both operators can be used before the variable reference—called prefix notation, like ...