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Problems with for loop

 
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Problems with for loop
Alianin
post 7 Oct, 2008 - 05:42 PM
Post #1


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Joined: 7 Oct, 2008
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I can't seem to find what the issue with my code is. I'm trying to calculate the sum of numbers from an array. Here is where I initialize the array:

CODE

    arrPrice[0] = .62;                //set amount for first element in price array
    
    for (int i = 1;i <= 19; i++)
    {
        arrPrice[i] = arrPrice[i-1] + .62;    //add .62 to previous price and set to new price
    }


And here is where I add it all up:

CODE

    sumPrice = 0;

    for (int i = 0;i <= 19; i++)
    {
        sumPrice = sumPrice + arrPrice[i];    //add price sum
    }


For some reason it's not adding correctly. It adds up correctly up to the 18th element and then when it hits 19 it just doubles the value of what 18 was. I hope I'm explaining this well enough.
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Martyr2
post 7 Oct, 2008 - 08:53 PM
Post #2


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Well I ran the code and appears to be working just fine. Here is my example and my output...

cpp

#include <iostream>
using namespace std;

int main() {
	double arrPrice[20];
	double sumPrice;

    arrPrice[0] = .62;                //set amount for first element in price array
    
    for (int i = 1;i <= 19; i++)
    {
        arrPrice[i] = arrPrice[i-1] + .62; //add .62 to previous price and set to new price
		cout << arrPrice[i] << endl;
	}

	sumPrice = 0;

    for (int i = 0;i <= 19; i++)
    {
        sumPrice = sumPrice + arrPrice[i];    //add price sum
    }

	cout << "Sum is: " << sumPrice << endl;
    return 0;
}


The output was....

CODE

1.24
1.86
2.48
3.1
3.72
4.34
4.96
5.58
6.2
6.82
7.44
8.06
8.68
9.3
9.92
10.54
11.16
11.78
12.4

Sum is: 130.2 (that is including the .62 at element 0)


So I am not sure what you are doing wrong. Run my test and see if you get the same results. If you do, obviously you are doing something wrong because I didn't change what you gave me other than putting in some output statements and making sure to define my variables as "double" (because you are handling decimals here).

Hope that helps. smile.gif
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Alianin
post 8 Oct, 2008 - 06:36 AM
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Joined: 7 Oct, 2008
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Wow. *slaps head* What a silly mistake to make. I declared my array 1 element short. Thanks for the brain jog Martyr!
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