Returns a non-empty string if EXPR is a reference, the empty string otherwise. If EXPR is not specified,$_ will be used. The value returned depends on the type of thing the reference is a reference to.
Builtin types include:
SCALARARRAYHASHCODEREFGLOBLVALUEFORMATIOVSTRINGRegexpYou can think ofref as atypeof operator.
if (ref($r) eq "HASH") { print "r is a reference to a hash.\n";}unless (ref($r)) { print "r is not a reference at all.\n";}The return valueLVALUE indicates a reference to an lvalue that is not a variable. You get this from taking the reference of function calls likepos orsubstr.VSTRING is returned if the reference points to aversion string.
The resultRegexp indicates that the argument is a regular expression resulting fromqr//.
If the referenced object has been blessed into a package, then that package name is returned instead. But don't use that, as it's now considered "bad practice". For one reason, an object could be using a class calledRegexp orIO, or evenHASH. Also,ref doesn't take into account subclasses, likeisa does.
Instead, useblessed (in theScalar::Util module) for boolean checks,isa for specific class checks andreftype (also fromScalar::Util) for type checks. (Seeperlobj for details and ablessed/isa example.)
See alsoperlref.
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