Need help with short program

Hello. In this short program I am calculating the amount of money a person spent paying a product off over x months.

Code:

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#include<iostream>
using namespace std;

int main()

{
    double amount, totalPay;
    int num, months;
   
   
    cout << "Enter how many months it took you to pay off the product: ";
    cin >> months;
   
    for(num = 1; num <= months; num++)
    {
            cout << "\nMonth " << num << ": \n" << "\tHow much did you pay? $";
            cin >> amount;
           
            totalPay = amount * num;
           
    }
           
    cout <<  "\nYou payed $" << totalPay << "\n" << endl;     
   
   
    return 0;
   
}

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The problem I am having is I don't know how to calculate the amount payed over the x months. Like for an example, if the user enters 3 months how do I get the amount payed for all of those 3 months. With my code right now I am only getting the amount for the last month, and not all 3. No matter what number I enter for months, I only get the last month's amount.

Initialize totalPay to 0 and then add amount * num to totalPay in the loop instead of straight assigning amount * num to totalPay like you're doing now.

Quote:

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Originally Posted by itsme86

Initialize totalPay to 0 and then add amount * num to totalPay in the loop instead of straight assigning amount * num to totalPay like you're doing now.

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Well I already have totalPay = num * amount in the loop, and when I assign totalpay to 0 it still gives me the same result. :/

Read what I suggested again. You're not adding amount * num to totalPay. Hint: Use the '+' or '+=' operator.

Quote:

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Originally Posted by itsme86

Read what I suggested again. You're not adding amount * num to totalPay. Hint: Use the '+' or '+=' operator.

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Well I think my code is wrong then because when I do

Code:

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totalPay += amount * num;

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and say I enter 3 months and $5, $10, and $15 dollar for months, I end up with a value of $70 when it should be $30.

Well that's because you're multiplying it by the number of months. You should really only be adding the amount for that month. You want:

totalPay = 0
month 1: 5
totalPay = 5
month 2: 10
totalPay = 15
month 3: 15
totalPay = 30

So what are you doing each time? You're adding the amount you paid that one month to totalPay: totalPay += amount

Quote:

---

Originally Posted by itsme86

Well that's because you're multiplying it by the number of months. You should really only be adding the amount for that month. You want:

totalPay = 0
month 1: 5
totalPay = 5
month 2: 10
totalPay = 15
month 3: 15
totalPay = 30

So what are you doing each time? You're adding the amount you paid that one month to totalPay: totalPay += amount

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oh wow thanks. I was using num because I thought it would need to keep track of how many months the user picks. Didn't realize you didn't need to do that.

Appreciate your help a lot.

EDIT: Also not sure why I had so much trouble with this. I just learned "keeping a running total" not that long ago.