prototype - get the prototype (if any) of a subroutine
Returns the prototype of a function as a string (or undef if the function has no prototype). FUNCTION is a reference to, or the name of, the function whose prototype you want to retrieve.
FUNCTION is a string starting with
CORE::, the rest is taken as a name for Perl builtin. If builtin is not overridable (such as
qw//) or its arguments cannot be expressed by a prototype (such as
system()) - in other words, the builtin does not behave like a Perl function -
returns undef. Otherwise, the string describing the equivalent prototype is returned.
If rather than formatting bugs, you encounter substantive content errors in these documents, such as mistakes in the explanations or code, please use the perlbug utility included with the Perl distribution.