sub looks_like_number { local $_ = shift; # checks from perlfaq4 return 1 unless defined; return 1 if (/^[+-]?\d+$/); # is a +/- integer return 1 if (/^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/); # a C float return 1 if ($] >= 5.008 and /^(Inf(inity)?|NaN)$/i) or ($] >= 5.006001 and /^Inf$/i); 0; }