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PERL exists Function



Syntax

exists EXPR


Definition and Usage

Returns true if the specified hash or array key exists, regardless of the corresponding value, even if it.s undef. If EXPR is a subroutine, then exists will return 1 if the subroutine has been declared (but not necessarily defined), 0 if not.

Return Value

  • 0 if hash element or array index does not exist, or if the subroutine has not been declared

  • 1 if hash element or array index does exist, or if the subroutine has not been declared

Example

Following are the usage...

    print "Exists\n" 	if exists $hash{$key};
    print "Defined\n" 	if defined $hash{$key};
    print "True\n"      if $hash{$key};

    print "Exists\n" 	if exists $array[$index];
    print "Defined\n" 	if defined $array[$index];
    print "True\n"      if $array[$index];

    print "Exists\n" 	if exists &subroutine_name;
    print "Defined\n" 	if defined &subroutine_name;


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