# Question in Parallel Arrays

• 03-29-2002
ProgrammingDlux
Question in Parallel Arrays
I'm trying to understand how parallel arrays work..how can I print the price of an item in one column and the difference between average and the price in the next column- for all ten items?

Code:

```#define Max 10 #include <iomanip.h> #include <stdlib.h>   main()   {  float Price[Max],Avg;int Diff; float Sum=0; int C; int Price[10];     for(C=0;C<Max;C++)       {Price[Max]=0;}     for(C=0;C<Max;C++)       { cout<<"\n Enter Price "<<C+1<<" : ";         cin>>Price[C];}     for(C=0;C<Max;C++)       { Sum=Sum+Price[C];}         Avg=Sum/9;       for(C=0;C<Max;C++)        this is the part where I don't know how to print price in one column and the difference between average and price in the next column..how?       {cout<<Price[C][Avg];}         cout<<"\n Sum = "<<Sum<<endl;         cout.setf(ios::floatfield, ios::showpoint);         cout.setf(ios::fixed);         cout<<setprecision(2);         cout<<Avg<<endl;       system("PAUSE");       return 0; }```
Thanks
• 03-29-2002
declare an array of known size to hold the names of the items:
char item[10]30];

declare an array of same size as first array to hold the price of the item
double price[10];

calculate average price or get it ffrom some other source

for each item in the array calculate the difference between the items price and the average price and store it in the average price price array.
double difference[10];

use a loop to display results:

for(i = 0; i < 10i++)
{
cout << item[i] << " has a price of " << price[i] << " which is " <<
difference[i] << " from the average price." << endl;
• 03-29-2002
ProgrammingDlux
I still don't understand :confused: is that example being used along with what I have or are those totally new variables? Does anyone have the time to explain it a little more clearly please?
• 03-30-2002
Shiro
>for(C=0;C<Max;C++)
> {Price[Max]=0;}

This seems not right to me. I guess you meant

Code:

```for(C=0;C<Max;C++)     {Price[C]=0;}```
You could declare a 2D array:

float Item [Max][2];

Where first column is the price and second column the difference between price and average.

Code:

```// get prices for (index = 0; index < MAX; index++) {     price = get_price ();     Item [index][0] = price; } // calculate average .... // calculate differences for (index = 0; index < MAX; index++) {     diff = Item [index][0] - avg;     Item [index][1] = diff; }```
Code:

```for (index = 0; index < MAX; index++)     cout << Item [index][0] << " "<< Item [index][1] << endl; would lead to price        diff column    column value      value value      value value      value```
• 03-30-2002
```double price[4]; double sum = 0; for(i = 0; i < 4; i++) {   cout << "enter price" << endl;   cin >> price[i];   sum += price[i]; } double avg = sum/4; long double difference[4]; for(i = 0; i < 4; i++) {  difference[i] = fabs(price[i] - avg); } for(i = 0; i < 4; i++) {   cout << "item " << i + 1 << " has price of " << price << " which    differs from the average price by " << difference << endl; }```