Inputting data into and sorting a struct

Question

I created a struct and created functions to perform several things on it. I am having trouble with the sortLength function, because when I run the program, only the data in the length gets sorted. Every thing else works fine although I am wondering if it is okay that my order is off a bit since I am using arrays which start their count at 0. I asked my professor for clarification and he told me if I have these (length and then widths) in the array and using comma to clearly separate them

10,8       4,3       6,5      5,1       2,1      3, 2  

Then it is sorted on length, then array will be:

2 ,1    3,2     4, 3     5,1      6,5     10,8

However, I am not getting that for my output. Here is the output I am getting.

Here are the instructions for the sortLength function.

Note that function will sort using the value for length of each rectangle (in ascending order).

You pick any algorithm to use; bubble, selection or insertion.

Remember that you are sorting an array!

---

#include "stdafx.h"
#include <iostream>

using namespace std;

struct RECTANGLE
{
    int length;
    int width;
    int area;
};

const int SIZE = 4;

// Function prototypes
void getValues(RECTANGLE[]);
void print(RECTANGLE[]);
int findMaxArea(RECTANGLE[]);
void sortLength(RECTANGLE[]);

int main()
{
    RECTANGLE arrRect[SIZE];
    //an array of type RECTANGLE

    int whereMax; //where find max area

    //put values to each element of array   
    getValues(arrRect);

    cout << endl << endl;

    //print out each element of array
    print(arrRect);

    whereMax = findMaxArea(arrRect);
    //find where max area is 

    cout << endl;

    cout << "Max area is " << arrRect[whereMax].area << " at position " << whereMax;

    cout << endl;

    sortLength(arrRect);  //sort base on Length

    cout << endl;

    //print out each element of array
    print(arrRect);

    return 0;
}

/**
* Pre-Condition: This function accepts an array of type RECTANGLE. 
* Post-Condition: It prompts the user for a length and width value
* and calculates the area. 
*/
void getValues(RECTANGLE arrRect[])
{
    //put values to each element of array   
    for (int i = 0; i<SIZE; i++)
    {
        cout << "\nEnter length and width : ";
        cin >> arrRect[i].length >> arrRect[i].width;

        arrRect[i].area = arrRect[i].length * arrRect[i].width;
        //calculate area
    }
}

/**
* Pre-Condition: This function accepts an array of type RECTANGLE. 
* Post-Condition: It prints the data for length, width, and area. 
*/
void print(RECTANGLE arrRect[])
{
    //print out each element of array
    cout << "Length       Width     Area" << endl;
    for (int i = 0; i<SIZE; i++)
    {
        cout << arrRect[i].length << "\t\t" << arrRect[i].width << "\t"
            << arrRect[i].area << endl;
    }
}

/**
* Pre-Condition: This function accepts an array of type RECTANGLE. 
* Post-Condition: It returns an int which represents the position 
* of the highest area in the data. 
*/
int findMaxArea(RECTANGLE arrRect[])
{
    int maxIndex = 0; 
    int max = arrRect[0].area; 

    for (int i = 0; i<SIZE; i++)
    {
        if (max < arrRect[i].area)
        {
            max = arrRect[i].area; 
            maxIndex = i; 
        }
    }
    return maxIndex;
}

/**
* Pre-Condition: This function accepts an array of type RECTANGLE. 
* Post-Condition: It sorts the data in the array according to the 
* length value. 
*/
void sortLength(RECTANGLE arrRect[])
{
    int temp;

    for (int i = 0; i < (SIZE - 1); i++)
    {
        for (int j = i + 1; j < SIZE; j++)
        {
            if (arrRect[i].length > arrRect[j].length)
            {
                temp = arrRect[i].length;

                arrRect[i].length = arrRect[j].length;

                arrRect[j].length = temp;
            }
        }
    }
}

Answer 1

You are getting the unexpected output since you are changing only the length field while sorting.

void sortLength(RECTANGLE arrRect[])
{
    int temp;

    for (int i = 0; i < (SIZE - 1); i++)
    {
        for (int j = i + 1; j < SIZE; j++)
        {
            if (arrRect[i].length > arrRect[j].length)
            {
                // ******  PROBLEM ******
                // The lines below swap only the length field.
                temp = arrRect[i].length;    
                arrRect[i].length = arrRect[j].length;
                arrRect[j].length = temp;
            }
        }
    }
}

What you should do is swap the entire object. Use

void sortLength(RECTANGLE arrRect[])
{
    // Make temp a RECTANGLE.
    RECTANGLE temp;

    for (int i = 0; i < (SIZE - 1); i++)
    {
        for (int j = i + 1; j < SIZE; j++)
        {
            if (arrRect[i].length > arrRect[j].length)
            {
                // Swap the entire object.
                temp = arrRect[i];    
                arrRect[i] = arrRect[j];
                arrRect[j] = temp;
            }
        }
    }
}