A decrement is a programming operator that decreases a numerical value of its operand by 1. In Perl, a variable can be decremented by one by adding a -- at the end of the variable. In the example below, the value variable is set as five and then decremented in value by one with the $value--; line. The last line prints the new value of the variable, which is four.
my $value = 5; $value--; print "$value\n";