The intent of this assignment was to show how to overload operators (in C++ code) – the calculator was an optional component for bonus points, and the operators used in the user input are just characters in string – not the programmatic operators we're talking about overloading (i.e., (re)defining the behavior of).

We worked with objects of a self-made class Rational that had numerators and denominators. We wrote code that allowed us to perform programmatic and mathematical operations on them and get sensible results – e.g. the overloaded "+" operator would add two Rationals together according to the rules for adding fractions.

The calculator was fiendishly difficult because there were all kinds of permutations of the 4 basic operations that had to be parsed correctly, made complicated by the fact that the symbol (/) indicated both division and two parts of a rational. Worse, the symbol (-) is for subtraction as well as indicating a negative integer, necessitating 16 different cases to handle: I had regular expressions with nicknames like "nominus-dualminus" ((n or n/n) - -n/-n) and "trailingminusonly-leadingminusonly" (n/-n - -n/n). Certain expressions like 3/2/3 (is that 3/2 divided by 3 (1/2), or 3 divided by 2/3 (9/2)?) would always be ambiguous and required prompting the user. I learned how to use regular expressions to identify the different kinds of fraction/operation combinations and build up the appropriate Rationals on which to perform the appropriate calculations.

In the end I gained a greater proficiency with regular expressions and using them in C++, and they're a critical (and, if this IT program is any indication, oft-neglected) part of a problem-solving toolkit.

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