API tonumber

Attempts to parse the number expressed in a string num = tonumber(str[, radix])

Arguments

 * str : String/number - this value will be converted to a numeric value.
 * radix : Number - An optional argument specifies the base to interpret the numeral. The base may be any integer between 2 and 36, inclusive. In bases above 10, the letter `A´ (in either upper or lower case) represents 10, `B´ represents 11, and so forth, with `Z´ representing 35. In base 10 (the default), the number may have a decimal part, as well as an optional exponent part. In other bases, only unsigned integers are accepted.

Returns

 * num : Number/nil - The argument as a numeric value or nil if the value cannot be converted.

Examples
tonumber("123") -- Returns 123

tonumber("argqerg") --Returns nil

tonumber("argqerg", 36) --Returns 4294967295

tonumber("13", 8) --Returns 11

tonumber ("D", 16) --Returns 13