CALCULATOR::Object-Oriented Programming

Objective

The objective of this project is to get a stronger grasp of object-oriented programming, get a better understanding of inheritance, and classes and their properties.

Background

Over the last few weeks we have covered multiple ways of implementing object oriented model; using the single file method of doing things, and multiple files method of doing things. Using that skill-set, you(we) must implement a program that will replicate the functions of a calculator.

Scope

For the scope of this project, as long as you implement a program that adopt the object-oriented methodology in C++ - there are no other particular restrictions.

Program

Replicate the functionality of a calculator, with the ability to accomplish multiple mathematical functions. Given a set of inputs the program must have the capability to compute the numbers based on the functions.

String Formating(fprintf) http://www.cplusplus.com/reference/cstdio/fprintf/

Standard Template Library http://www.cplusplus.com/reference/stl/

Vector Reference http://www.cplusplus.com/reference/vector/vector/

TYPEDEF

As a follow to our discussion this week, typedef is a naming convention used in C/C+, its primary use case is to declare various data-types. Defining data types in C can be a tedious task, some data types and variables names only can up to 1/2 of an 80-85char line of code, which ultimately will result in either unreadability, or some very extensive lines. Here is a brief example of how typedef could come in handy.

unsigned long long int a_very_long_variable_name = some+expressions+here;

an optimization for this line would be the following:

typedef unsigned long long int ulli_t; 
ulli_t a_very_long_variable_name = some+expressions+here; 

//much cleaner than the above version(could be better)

Although typedef appears to be defining only types, it removes some overheads down the road as a developer,it provides consistency, and clarity when used effectively.

UNDEF

Undef is a directive in that is available in C and C++. It as the form of #undef when called. Undef is used as a complement to the #define, as a preprocessor directive it is used to enclosed a #define statement to make sure there is no naming conflict and constrict one's logic within a set of code. Let's take a macro for example it is efficient for macros primarily because of the fact that it does common tasks such print, as many modules take have various print functions, the ideal way to make sure there is no conflict is to use undef. This is how it is used:

    #define pprintf1() //for pretty-printf
    #undef pprintf1()

easy peasy!

Quick Tip:

Recently I have discovered a trick that could help run scripts much quicker with direct access to one's lab46 account, without working only on a single machine at a time. Ultimately, I had to ssh into my account, and whenever I left the terminal open for a few minutes, it would go offline - or had to share scripts between my personal laptop and lab46 machines, and work on projects on one machine at a time(fairly painful). With this method one can easily call commands anywhere, that are otherwise only available on the lab46 account. Here is how it is accomplished:

    system("ssh account@lab47.corning-cc.edu command_here");

A working example would be the following:

     //From my own laptop
     system("ssh user@lab46.corning-cc.edu status cprog")
     
     //This example would return grades from the user.

Note that the script would prompt you to enter your password.