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Perl Programming/Keywords/undef
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Perl umask UNITCHECK Keywords
The undef keyword
undef undefines the expression that follows the function. The expression must be an lvalue. This function is used only on scalars, arrays (using @), a hash (using %), a subroutine (using &), or a typeglob (using *).
Syntax
undef EXPR
Perl umask UNITCHECK Keywords