In C#, the only language built-in to convert a string to an integer with a specified base is Convert.ToInt32(string value, int fromBase). However, this only allows conversions from base 2, 8, 10, and 16. What if you wanted to convert a string to an integer from any arbitrary base within 2 <= fromBase <= 36?

Task Overview

Write a method StringExtensions.Parse(this string value, int fromBase) which will convert the string representation of a number with a base where the base is within the range of 2 to 36, inclusive, into an Int32.

Documentation:

StringExtensions.Parse Method (String, Int32)

Returns an Int32 which represents the string. The string's base is specified by the second argument.

Syntax

Constraints

• The behavior for Parse is only defined for 2 <= fromBase <= 36. If fromBase is out of that range, throw an ArgumentException.
• The string passed into Parse will not contain a negative sign, '-', but the return value may still be negative. For example, if "FFFFFFFF.Parse(16)" is called, the resulting value would be -1 (this is the same behavior as Convert.ToInt32("FFFFFFFF", 16)).
• The string passed into Parse can only contain numbers, lowercase letters, and uppercase letters. An uppercase variant of a letter has the same value as its lowercase variant, e.g. "a".Parse(11) == "A".Parse(11).