Read a .txt file, calculate sum and mean

Question

I have a .txt file which contains numbers and looks like this:

1
2
3

etc

The numbers are unimportant but they all start on a new line.

I want to then find the sum & mean of the numbers in the text file.

Here's what I have so far:

#include<cmath>
#include<cstdlib>
#include<iomanip>
#include<string>
#include<fstream>
using namespace std;

int main(int argc, char * argv[])
{
    std::fstream myfile("numbers.txt", std::ios_base::in);

    float a;
    while (myfile >> a)
    {
        printf("%f ", a);
    }

    getchar();

    return 0;

int sum(0);
int sumcount(0);
double average(0);
int even(0);
int odd(0);

ifstream fin;

string file_name;

int x(0);

cout<<"numbers.txt";
cin>> file_name;
fin.open(file_name.c_str(),ios::in);

if (!fin.is_open())
{
    cerr<<"Unable to open file "<<file_name<<endl;
    exit(10);

}

fin>>x;
    while (!fin.fail())
    {
        cout<<"Read integer: "<<x<<endl;
        fin>>x;
        sum=sum+x;
        sumcount++;
        if(x%2==0)
            even++;
        else
            odd++;

    }

    fin.close();
    average=(double)sum/sumcount;
    cout<<"Sum of integers: "<<sum<<endl;
    cout<<"Average: "<<average<<endl;
    cout<<"Number of even integers: "<<even<<endl;
    cout<<"Number of odd integers: "<<odd<<endl;

    return 0;
}

The start loads the numbers but it won't execute the next step.

i have looked at a lot of other code and tried to implement other ideas to solve the problem; however, some people use loops and arrays and other things and I'm not sure which to use.

How can I get my program to find the sum and mean of numbers in the file?

also any other links for help would be appreciated

EDIT: although the numbers are intergers the mean may not be

Tip #1: an unconditional `return 0;` at the almost-beginning of `main()` is usually bad idea, your program will not continue after that line. — quetzalcoatl, Oct 20 '15 at 22:26

Mykola · Accepted Answer · 2015-10-20T23:43:14.330

Here is your working code.

#include <cmath>
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <string>
#include <fstream>


using namespace std;

int main(int argc, char * argv[])
{
    std::fstream myfile("numbers.txt", std::ios_base::in);

    float a = 0;

    myfile >> a;

    while (!myfile.fail())
    {
        printf("%f ", a);
        myfile >> a; // here you dispay your numbers
    }

    getchar(); // waiting for input

    float sum(0);
    int x(0);
    int sumcount(0);
    double average(0);
    int even(0);
    int odd(0);

    ifstream fin;

    string file_name;

    cout<<"numbers.txt" << endl;

    cin>> file_name; // waiting for enter file name

    fin.open(file_name.c_str(),ios::in);

    if (!fin.is_open())
    {
        cerr<<"Unable to open file "<<file_name<<endl;
        exit(10);
    }

    fin >> x;

    while (!fin.fail())
    {
        cout<<"Read integer: "<<x<<endl; // display number again

        sum=sum+x;
        sumcount++;
        if(x % 2==0)  // compuing your file statistics
            even++;
        else
            odd++;

        fin>>x;
    }

    fin.close();
    average=(double)sum/sumcount;

    cout<<"Sum of integers: "<<sum<<endl; // displaying results
    cout<<"Average: "<<average<<endl;
    cout<<"Number of even integers: "<<even<<endl;
    cout<<"Number of odd integers: "<<odd<<endl;

    return 0;
}

I have added some minimal alteration to make your program work correctly.

the result

and more

thank you - im using xcode and my output just gives me the numbers in my file not the sum or mean - do you know why? — Jack, Oct 20 '15 at 23:00
and you must know what you code is doing, its clear that you do not understand what your program does. — Mykola, Oct 20 '15 at 23:21
I have post my result. and I have not idea why it is not working for you. — Mykola, Oct 20 '15 at 23:44

ArchLinuxTux · Answer 2 · 2015-10-20T22:43:45.850

0

#include <iostream>
#include <fstream>
using namespace std;


int main() {

int n=0;
int sum=0,total=0;

fstream file("numbers.txt");
while(file >> n) // or while(cin >> n) to read from stdin, commandline
{
    sum += n;
    total++;
}

int average = (float) sum/total;

cout<<"sum: " << sum << endl;
cout << "average: " << average << endl;
return 0;
}

edited Oct 20 '15 at 22:43

answered Oct 20 '15 at 22:34

ArchLinuxTux

840
1
11
28

score 0 · Answer 3 · answered Oct 20 '15 at 22:36

0

As soon as your main function encounters the statement return 0 it will exit the program and fail to execute the remaining code. This should generally appear only once in your main function, at the end of your code block

answered Oct 20 '15 at 22:36

David Loughnane

143
1
3
11

score 0 · Answer 4 · answered Oct 20 '15 at 23:20

0

#include <iostream>
#include<fstream>

int main()
{
    std::ifstream txtFile;
    txtFile.open("data.txt");
    //TODO: check if the file fails to open.

    double tempNum, mean(0.0), sum(0.0), count(0.0);
    while (txtFile >> tempNum)
    {
        sum += tempNum;
        ++count;
    }
    mean = sum/count;
    std::cout << "mean: " << mean << "  sum: " << sum << std::endl;

    return 0;
}

answered Oct 20 '15 at 23:20

CroCo

5,531
9
56
88

I didn't see all answers. – CroCo Oct 20 '15 at 23:45

Read a .txt file, calculate sum and mean

4 Answers4