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Symbolic Unary Operators

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Symbolic Unary Operators

Unary ``!'' performs logical negation, i.e., ``not''. See also not for a lower precedence version of this.

Unary ``-'' performs arithmetic negation if the operand is numeric. If the operand is an identifier, a string consisting of a minus sign concatenated with the identifier is returned. Otherwise, if the string starts with a plus or minus, a string starting with the opposite sign is returned. One effect of these rules is that -bareword is equivalent to "-bareword".

Unary ``~'' performs bitwise negation, i.e., 1's complement. (See also Integer Arithmetic.)

Unary ``+'' has no effect whatsoever, even on strings. It is useful syntactically for separating a function name from a parenthesized expression that would otherwise be interpreted as the complete list of function arguments. (See examples above under Terms and List Operators (Leftward).)

Unary ``\'' creates a reference to whatever follows it. See the perlref manpage. Do not confuse this behavior with the behavior of backslash within a string, although both forms do convey the notion of protecting the next thing from interpretation.

Source: Perl operators and precedence
Copyright: Larry Wall, et al.
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