Sorting Two Sets of Data in Parallel Array

Question

I'm currently having a real difficult time trying to sort my array (I really need to work on this, I always have trouble sorting data).

So basically I have created a C++ struct that contains a "date" and "snowDepth" element. I have used bubblesort logic to sort the snowDepth element, which is awesome and that's exactly what I need. However, since the elements are separate, the dates don't change. How can I sort a parallel array??

Data should look like this:

  Snow Report  December 12 - 18
      Date            Base
       13             42.3
       12             42.5
       14             42.8
       15             43.1
       18             43.1
       16             43.4
       17             43.8

and mine looks like this:

    SNOW REPORT    December 12 - 18
=======================================
       DATE             DEPTH
        12              42.3
        13              42.5
        14              42.8
        15              43.1
        16              43.1
        17              43.4
        18              43.8

Notice how the dates aren't sorted along with the snowDepth element. How can I accomplish this?

Okay, thanks for all the comments guys!! Here is my code:

// Structure
struct Array
{
    int date;
    double snowDepth;

    void SnowData(int d, double sD)
    {
        date = d;
        snowDepth = sD;
    }
};

// Main Function
int main()
{
    /* *--------------------*
       |      VARIABLES     |
       *--------------------* */

    // Constant Variables
    const int NUM_ELEMENTS = 7;
    const int NUM_MONTHS = 12;

    // String, Numerical, and Boolean Variables
    string month;
    int startDate;
    int endDate;
    int a;
    int b;
    int flag = 0;
    double result;
    bool monthMatch = false;

    // Array Variables
    Array snowData[NUM_ELEMENTS];
    string name[NUM_MONTHS] = {"January", "February", "March",
                               "April",   "May",      "June",
                               "July",    "August",   "September",
                               "October", "November", "December"  };


    /* *--------------------*
       | USER  INSTRUCTIONS |
       *--------------------* */    

    cout << endl;
    cout << "This program will keep track of the local snow conditions for 7 days." << endl;
    cout << "This program will ask the user for the month, date range (must be 7 days)," << endl;
    cout << "and the inches of snow reported on that date.  The program will then sort" << endl;
    cout << "the data from least amount of snow reported to the most." << endl;
    cout << endl;


    /* *--------------------*
       |     USER PROMPT    |
       *--------------------* */

    // Prompt the user for the month
    cout << "Enter the full name of the month: ";
    cin >> month;

    // Prompt the user for the starting date
    cout << "Enter the starting date of the 7-day period: ";
    cin >> startDate;
    snowData[0].date = startDate;

    // Once the user enters the start date, run a loop to initialize the rest of the dates in snowData array
    for (int x = 1; x < NUM_ELEMENTS; x++)
        snowData[x].date = ++startDate;

    // Prompt the user for the ending date
    cout << "Enter the ending date of the 7-day period: ";
    cin >> endDate;
    cout << endl;

    // If the user does not enter the correct ending date (which is 7 days from the start date), loop will prompt the user again
    if (endDate != snowData[NUM_ELEMENTS - 1].date)
    {
        do
        {
            cout << "The end date entered is not 7 days from the start date. Try again." << endl;
            cout << "Enter the ending date of the 7-day period: ";
            cin >> endDate;
            cout << endl;

        } while (endDate != snowData[NUM_ELEMENTS - 1].date);

        int x = 0;

        // Once the user enters the correct ending date, prompt the user for the snow depth numbers
        for (int y = 0; y < NUM_ELEMENTS; y++)
        {
            cout << "Enter the depth of snow measured on " << month << " " << snowData[x].date << ": ";
            cin >> snowData[y].snowDepth;
            x++;
        }
    }

    // Once the user enters the correct ending date, prompt the user for the snow depth numbers
    else
    {
        int x = 0;

        for (int y = 0; y < NUM_ELEMENTS; y++)
        {
            cout << "Enter the depth of snow measured on " << month << " " << snowData[x].date << ": ";
            cin >> snowData[y].snowDepth;
            x++;
        }
    }

    /* *--------------------*
       |  SORTING & FORMAT  |
       *--------------------* */

    // Sorting logic in ascending order
    for (a = 1; (a <= NUM_ELEMENTS) && flag; a++)
    {
        flag = 0;

        for (b = 0; b < (NUM_ELEMENTS - 1); b++)
        {
            if (snowData[b + 1].snowDepth < snowData[b].snowDepth)
            {
                result  = snowData[b].snowDepth;                
                snowData[b].snowDepth = snowData[b + 1].snowDepth;                
                snowData[b + 1].snowDepth = result;

                flag = 1;
            }
        }
    }

    // Formatted Output
    cout << endl;
    cout << "    SNOW REPORT    ";
    cout << month << " " << snowData[0].date << " - " << snowData[6].date << endl;
    cout << "=======================================" << endl;
    cout << setw(11) << "DATE" << setw(18) << "DEPTH" << endl;

    for (int x = 0; x < (NUM_ELEMENTS); x++)
        cout << setw(10) << snowData[x].date << setw(18) << snowData[x].snowDepth << endl;

    cout << endl;
}

Answer 1

You could create a struct for a single date/snowDepth pair, and keep an array of such pairs. After you could add more fields there, and sort by whatever you like. The data will always be consistent.

By the way: why bubble sort? Quicksort is much faster.