Program that shows sum of even numbers - while-loop

Question

I have a problem for my CS class that I'm just not getting. I have to read an unspecified amount of integers in a text file. From there on I have to find the integers that are divisible by 5 and then add them up. Say I have a text file containing 1, 5, 7, 10, and 11, so my answer should be 15. The instructor says we have to use a while loop to read until End-Of-File.
Here is what I have, which is completely wrong:
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
int sum, even;
sum = 0;
ifstream inFile;
inFile.open("numbers.txt");
inFile >> even;
do
{
if (even % 5 == 0)
{
sum = sum + even;
cout << "\nThe sum of the numbers is:" << sum << endl;
}
else
{
cout << "\nNo numbers divisible by 5." << endl;
}
}
while (!inFile.eof());
inFile.close();
system("pause");
return 0;
}
Something does happen; an endless loop that goes through large negative numbers.
Can anyone point me into the right direction?
Thanks,
Tobi
Update: I have this so far, but it prints out 4 answers.
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
int num, sum, count;
sum = 0;
ifstream inFile;
inFile.open ("numbers2.txt");
if (!inFile)
{
cout << "Can't open the input file.\n" << endl;
system("pause");
return 1;
}
inFile >> num;
while (!inFile.eof())
{
inFile >> num;
if (num % 5 == 0)
{
sum += num;
cout << "Sum is: " << sum << endl;
}
else
{
cout << "Is not divisible by 5." << endl;
}
}
inFile.close();
system("pause");
return 0;
}
My output looks like this:
sum is: 5
sum is: 25 (What I want as the output)
Is not divisible by 5.
Is not divisible by 5
I'll keep trying until I get this.
Thanks to everyone who has answered so far.

Answer 1

You can try something like this...not perfect, but just something you can use to understand and improve upon.
C++ example - program.cpp
#include <iostream> // provides cout, endl etc.
#include <fstream> // provides file stream functionality
#include <string> // provides string
#include <stdlib.h> // provides atoi functionality
using namespace std;
int main()
{
int sum = 0;
int num = 0;
bool multiple_of_5_found = false;
std::ifstream file("numbers.txt");
std::string str;
// while begins
while(std::getline(file, str))
{
// convert string to number
num = atoi(str.c_str());
if (num % 5 == 0)
{
multiple_of_5_found = true;
sum += num;
}
}
// while ends
// based on what we observed/calculated, print info
if (multiple_of_5_found)
{
cout << "The sum of numbers divisible by 5 is "
<< sum << endl;
}
else
{
cout << "No number divisible by 5" << endl;
}
return 0;
}
GCC version
$> g++ --version
g++-4.7.real (Debian 4.7.2-5) 4.7.2
numbers.txt
$ cat numbers.txt
1
5
7
10
11
15
compile and run
$ g++ program.cpp && ./a.out
The sum of numbers divisible by 5 is 30
Visual Studio 2013 screenshot of numbers.txt resource
Visual Studio 2013 screenshot of Source.cpp
Visual Studio 2013 screenshot after pressing F7 and clicking on Local Windows Debugger