Saturday, November 28, 2009

Gaining Familiarity with C++

Today I decided to solidify my familiarity of C++ by creating a couple rather useless, but working programs from scratch.

The first one I created solves for the hypotenuse vector of a right triangle, using the Pythagorean Theorem. This program is rather straightforward, and took little to no time to write.

// Hypotenuse

#include <iostream>
#include <cmath>
#include <cstdlib>
using namespace std;

int main()
    int x;   //position of x-axis
    int y;   //position of y-axis
    int A;   //square A + square B
    float V;   //resultant vector
    cout << "Enter in both adjecants." << '\n';
    cin >> x;
    cin >> y;
    A = (x * x) + (y * y);
    V = sqrt ((double) A );
    cout<< V << "\n";   //output of resultant vector
    return 0;

After creating this program in a few minutes, I went on to try something a bit more challenging. This program below took me about two hours to write; a lot of debugging. At first, I tried to write the entire program within the main function, although, that didn't really challenge me or enhance my abilities in any way, and it was extremely buggy. I decided to seperate each step in the process of matrix multiplication into seperate functions, and create my main function as a do while loop. It turned out producing correct results! Here is the code, keep in mind this only works with 2x2 matrices:

using namespace std;

/*The functions in this program are fired in the order of top to bottom for readability*/

void Readmatrix(int a, int b, int c, int d, int e, int f, intg, int h)

/*This function records the integers placed into each matrices' variable*/

        cout << "Enter in your first matrix (4 integers): ";
        cin >> a;
        cin >> b;
        cin >> c;
        cin >> d;
        cout << "Enter in your second matrix (4 integers): ";
        cin >> e;
        cin >> f;
        cin >> g;
        cin >> h;

void multiply(int a, int b, int c, int d, int e, int f, intg, int h)

/*This is the algorithm for multiplying the matrices together. It is only compatible with 2x2 matrices*/

        int a1, b1, c1, d1 = 0;
        a1 = ((a * e) + (b * g));
        b1 = ((a * f) + (b * h));
        c1 = ((c * e) + (d * g));
        d1 = ((c * f) + (d * h));
        a = a1;
        b = b1;
        c = c1;
        d = d1;


void Displaymatrix(int a, int b, int c, int d)

/*The functions simply displays the 2x2 matrix product*/

        cout << a << " " << b << '\n' << c << " " << d;

int main()

/*The functions is my main loop, which calls all the above functions*/

        char rawr;
                int a, b, c, d, e, f, g, h = 0;

                Readmatrix(a, b, c, d, e, f, g, h);
                multiply(a, b, c, d, e, f, g, h);
                Displaymatrix(a, b, c, d);
                cout << endl;
                cout <<"Would you like to do another matrix (y/n)? ";
                cin >> rawr;
                cout << endl;
        } while ((rawr == 'y') || (rawr == 'Y'));


I feel like I'm getting a little better each day I do this! Tomorrow, I plan to write out a program that will add, subtract, and reduce fractions. I will be using a reference source code, found here:

I can't wait to start moving onto programs using windows coding! I plan to become accustomed to using arrays, functions, structures, pointers, and dynamic memory before I move onto more advanced concepts though. If I can write simple programs using the tools I just listed, I'll have some fundamental skills to use for those more advanced concepts.


  1. Heh, pretty good. Course, programming a game will be more complex than this, but you'll be there soon enough.

  2. Hey thanks! Follow along with me if you want :D

    Once I hit college, I'll be posting what I learn here on this blog. Might be cool to follow along with me till then, so we can all start at the same level.

  3. "This took me about 2 hours to complete, and about 25 minutes to write. Yep, that means I sat there and debugged the program for over an hour and a half. Sheesh, I hope this isn't what programming is always like ;)"

    If you think half an hour of debugging is a lot, you're in for a nasy surprise. I've been known to a week working on a single bug, multiple hours a day. :P

  4. Hour and a half, not half an hour. I didn't actually think it was significant, it was just very annoying- hence my winking face ;)


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