Test given string to determine whether it is a numeric string
BOOL is_numeric( LPCSTR lpcstr, BOOL bThousoudSeparatorOK = TRUE, BOOL bLeadZeroOK = TRUE, BOOL bIgnoreRegionalNumeric = false )
TRUE if given string is numeric, otherwise FALSE.
EX1
double is_numeric_ex1(string str = "0.12545") { if (is_numeric(str)) return atof(str); else return NANUM; }
origin.h