recConvert

/***************************************************************************************
* Author:                       Jared Hughes
* Date Created:                 11/1/2014
* Last date Modified:           11/2/2014
* Filename:                     recConvert.cpp
*
* Overview:
*   This program will either take a decimal number or binary number from user input
*   and convert the number to the other option (dec -> bin || bin -> dec).  The third
*   menu option is to simply end the program.
*
* Input:
*   Simple input obtained from the user includes a int data type decimal base 10 number
*   or a binary number (base 2).
*
*       Example: Decimal = 10
*                Binary = 1010
*
* Output:
*   Output of this program will be a simple decimal or binary number given to the user
*   after conversion.
*
*       Example:  Input decimal - > 10
*                 Output binary - > 1010
*
****************************************************************************************/
#include <iostream>
#include <cstdlib>
#include <string>
#include <cmath>
using namespace std;

string tobinary(int decimal_to);        //function to convert decimal number to binary
int todecimal (string binary_to);       //function to convert binary to decimal

int main()
{
    int menu;               //menu selection
    string binary;          //intial binary string to be converted
    int decimal;            //decimal number input to be converted
    char again;             //while loop to repeat program

    do
    {
        cout << "\nThis is a number converting program.\n\n";
        cout << "1. Binary to decimal conversion.\n";
        cout << "2. Decimal(as integer) to binary conversion.\n";
        cout << "3. Exit program.\n";
        cout << "\nPlease enter your choice: ";
        cin >> menu;
        cin.ignore(256, '\n');

        //Validate that a correct menu choice was made
        while(menu < 1 || menu > 3)
        {
            cout << "\nPlease select a VALID choice.\n";
            cout << "1. Binary to decimal conversion.\n";
            cout << "2. Decimal to binary conversion.\n";
            cout << "3. Exit program.\n";
            cout << "\nPlease enter your choice: ";
            cin >> menu;
            cin.ignore(256, '\n');
        }

        //Binary to decimal
        if(menu == 1)
        {
            cout << "You have selected binary to decimal.\n";
            cout << "Please enter a number to be converted.\n";
            getline(cin, binary);

            validate:

            for(int x = 0; x < binary.length(); x++)
            {
                if(binary.at(x) != '1' && binary.at(x) != '0')
                {
                    cout << "Please enter a valid binary number.\n";
                    getline(cin, binary);
                    goto validate;
                }
            }

            cout << "Your decimal equivalent of " << binary << " is: ";
            cout << todecimal(binary) << endl;
        }

        //decimal to binary
        if(menu == 2)
        {
            cout << "You have selected decimal to binary.\n";
            cout << "Please enter an integer to be converted.\n";

            while (!(cin >> decimal))
            {
            cin.clear();
            cin.ignore(1000, '\n');
            cout << "Please enter a valid integer: ";
            }

            cout << "Your binary equivalent of " << decimal << " is: ";
            cout << tobinary(decimal) << endl;


        }

        //end program
        if(menu == 3)
        {
            cout << "This program is concluded.\n";
            return 0;
        }

        cout << "Would you like to start again? (Y/N)";
        cin >> again;
        cin.ignore(256, '\n');
        cout << endl;

    //repeat program
    }while(again == 'Y' || again == 'y');

    return 0;
}

/***********************************************************
* Entry: decimal_to is the input decimal from int main().
*
* Exit: Will return to main when decimal_to == 0
*       Will return the binary equivalent of decimal_to in
*       a string data type.
*
* Purpose: To convert a binary number to a decimal.
************************************************************/

string tobinary (int decimal_to)
{
    string from_decimal = "";               //string to hold the binary number

    if(decimal_to == 0)
    {
        return from_decimal;
    }

    else if((decimal_to % 2) > 0)
    {
        from_decimal += '1';
        (decimal_to /= 2);
        return (tobinary(decimal_to) + from_decimal);
    }

    else
    {
        from_decimal += '0';
        (decimal_to /= 2);
        return (tobinary(decimal_to) + from_decimal);
    }
}


int todecimal(string binary_to)
{
    int power_factor;
    long temp_num;

    power_factor = binary_to.length()-1;

    temp_num = pow(2, power_factor) * (binary_to.at(0) == '1' ? 1 : 0);

    if(power_factor > 0)
    {
        return temp_num + todecimal(binary_to.substr(1, power_factor));
    }

    else
    {
        return temp_num;
    }
}