Correction: isnum('') returns 1, so here is a better version 
sub isnum ($) {
    return 0 if $_[0] eq '';
    $_[0] ^ $_[0] ? 0 : 1
}

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In reply to Re^2: 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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