C++ beginner - Sum of multiples less than 100

Hey guys, this is my first post here. I am a beginner in C++ and have a question for a homework assignment. I have read my book over and over and can't seem to figure out how to code this properly.

What I want it to do is have the user input a number: ex. 5 and then have the code give the sum for all the multiples of 5 less than 100, so it should be equal to 950 in this example.

Anyway, I have got so far to get it to list the numbers, but I need the sum of those numbers without all the text displayed every time.

I have chosen to use the FOR, but I am wondering if I should implement WHILE loop in my coding somewhere. I just don't know how to go about it for this problem.

Again, this is my first post (and definitely not my last!) I hope I have read the rules properly. It is my first programming class in school, and I am seeing a tutor tomorrow and the next day, I would just like to have a better grasp of this before going in tomorrow.

Code:

---

#include <iostream>
using namespace std;

int addMultiples()
{
  // Start
  cout << "What multiples are we adding? ";
  int start;
  cin >> start;

  int increment = start;

  for (int count = start; count <= 100; count += increment)
  cout << "The sum of multiples of " << start
        << " less than 100 are: " << count << endl;

  return 0;
}




int main()
{
  addMultiples();
  return 0;
}

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I want the output like this:

What multiples are we adding? 5
The sum of the multiples of 5 less than 100 are: 950

Thanks for your help and explanations!

A for loop is fine. At the moment, the problem is that you are not adding up the multiples of 5 (or whatever it is).

I suggest that you change your addMultiples function to take start as an argument, and to return the result. The input/output should all be done in the main function instead.

Quote:

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Originally Posted by laserlight

A for loop is fine. At the moment, the problem is that you are not adding up the multiples of 5 (or whatever it is).

I suggest that you change your addMultiples function to take start as an argument, and to return the result. The input/output should all be done in the main function instead.

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Thanks I will try to change the function to getMultiple, then have a function run the FOR loop. Any advice on how to get the sum from a loop?

Thanks again, I feel I am on the right track!

Quote:

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Originally Posted by Bronzy

Any advice on how to get the sum from a loop?

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You need another variable, such as "sum", that is initialized to zero, and you need to add count to that sum for each iteration of the loop.

Quote:

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Originally Posted by Bronzy

Any advice on how to get the sum from a loop?

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Tried making a flowchart?

Thanks for the help guys, I was able to have main call a few separate functions, I was missing the curly braces for the loop to get the Sum.

Cheers!

Code:

---

#include <iostream>
using namespace std;


/**********************************************************************
 * getMultiple prompts the user for the multiple they want.
 ************************************************************************/
int getMultiple()
{
  cout << "What multiples are we adding? ";
  int number;
  cin >> number;
  return number;
}


/**********************************************************************
 * addMultiples initiates a loop for the multiple and sums the data.
 ************************************************************************/
int addMultiples(int multiple)
{
  int sum = 0;
  int end = 100;


  for (int count = multiple; count < 100; count += multiple)
  {
      sum += count;
  }


  return sum;
}


/**********************************************************************
 * Display outputs the sum of the multiples to the user.
 ************************************************************************/
void display(int multiple, int sum)
{
  cout << "The sum of multiples of "
        << multiple
        << " less than 100 are: "
        << sum
        << endl;


  return;
}



/**********************************************************************
 * Main calls the other functions in the program
 ************************************************************************/
int main()
{
  int multiple = getMultiple();
  int sum = addMultiples(multiple);


  display(multiple, sum);


  return 0;
}

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Looks good. I note that you forgot to use the end variable in addMultiples though.

Quote:

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Originally Posted by laserlight

Looks good. I note that you forgot to use the end variable in addMultiples though.

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Aha, you are right! I'll change that too :)