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``++'' and ``--'' work as in
C. That is, if placed before a variable, they
increment or decrement the variable before returning the value, and if
placed after, increment or decrement the variable after returning the
The auto-increment operator has a little extra builtin magic to it. If you
increment a variable that is numeric, or that has ever been used in a
numeric context, you get a normal increment. If, however, the variable has
been used in only string contexts since it was set, and has a value that is
not null and matches the pattern
/^[a-zA-Z]*[0-9]*$/, the increment is done as a string, preserving each character within its
range, with carry:
print ++($foo = '99'); # prints '100'
print ++($foo = 'a0'); # prints 'a1'
print ++($foo = 'Az'); # prints 'Ba'
print ++($foo = 'zz'); # prints 'aaa'
The auto-decrement operator is not magical.
Source: Perl operators and precedence
Copyright: Larry Wall, et al.
Previous: The Arrow Operator
(Corrections, notes, and links courtesy of RocketAware.com)
Up to: Integer math
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