Thanks to the sugestions above i have the function isnum: 
sub isnum ($) { $_[0] ^ $_[0] ? 0 : 1 }

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XORing a number gives zero, so the function returns 1. XORing a string gives a string of nulls, still a non-empty string, so the function returns 0

In reply to Re: How to check if a scalar value is numeric or string? by ibravos
in thread How to check if a scalar value is numeric or string? by bgupta

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