WARNING: Bad code. I found this on my old computer and thought it was interesting to see my parsing before I knew any parsing. I was 16 and teaching myself C++ for the first time when I wrote this.

main.cpp

#include <iostream>
#include <cstdlib>

using namespace std;

int add(int a, int b){
    return a+b;
}

int subtract(int a, int b){
    return a-b;
}

int multiply(int a, int b){
    return a*b;
}

int divide(int a, int b){
    return a/b;
}

int power(int a, int n){
    return a^n;
}

int root(int a, int n){
    return a^(1/n);
}

int main(int argc, char* argv[]){
    bool done = false;
    int i = 1;
    int u = 0;
    do{
        if(argv[i][u] == '\0'){
            if(argv[i][u+1] == 'R'){
                done = true;
            }else{
                i++;
            }
        }

        if(argv[i][u] == '+'){
            string temp = "";
            for(int c = 0; c < u; c++){
                temp += argv[i][c];
            }
            int a = atoi(temp.c_str());
            bool fin = false;
            int v = -1;
            do{
                v++;
                if(argv[i][v] == '\0'){
                    fin = true;
                }
            }while(!fin);
            temp = "";
            for(int c = u; c < v; c++){
                temp += argv[i][c];
            }
            int b = atoi(temp.c_str());
            cout << add(a, b) << endl;
        }else if(argv[i][u] == '-'){
            string temp = "";
            for(int c = 0; c < u; c++){
                temp += argv[i][c];
            }
            int a = atoi(temp.c_str());
            bool fin = false;
            int v = -1;
            do{
                v++;
                if(argv[i][v] == '\0'){
                    fin = true;
                }
            }while(!fin);
            temp = "";
            for(int c = u; c < v; c++){
                temp += argv[i][c];
            }
            int b = atoi(temp.c_str());
            cout << subtract(a, b) << endl;
        }
        u++;
    }while(!done);

    return 0;
}

MathClass.txt

//////////////////////////////////////////////
//                                          //
//  MathClass:                              //
//     version  = 0.01 planning             //
//     modified = 08/09/2010                //
//     license  = GPL                       //
//                                          //
//////////////////////////////////////////////

TODO:
    Addition
    Subtraction
    Multiplication
    Division
    Powers
    Roots

    Mean
    Median
    Range
    Mode    

    Scientific notation
    Order of operations
    constants

    Coversion

    Distance Formula
    Slope Formula
    Midpoint
    
    Trig Functions
    Logarithms    

    Imaginary numbers
    Complex numbers
    
    Lists
    Matricies??

    Sequences
    Summation

    Solve right Triangles -> solve triangles