[SOLVED] Why the answer for the sum and the average wrong??

[Ashieboy]

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

int main(){
string line;
float x,sum=0,average,b;
int y=0,i,j,k=0;
float n1[1000];
float n2[1000];

ifstream myfile("sensor.txt");

if(myfile.is_open())
{
    getline(myfile,line);
    while(myfile.good())
    {
        myfile>>x;
        n1[y]=x;
        y=y+1;

    }myfile.close();

    for(i=0;i<y;i++)
    {
        sum=sum+n1[i];
    }
    average=sum/y;
    cout<<"The sum of the number is "<<sum<<endl;
    cout<<"The average is "<<average<<endl;
    cout<<"\nThe number larger than average"<<endl;

for(i=0;i<y;i++)
{
    b=n1[i];
    if(b>average)
    {
        cout<<n1[i]<<endl;
    }
    else
    {
        continue;
    }
  }
}
else{cout<<"\nunable to open";}
}

 

[horace1]

why do you have

    getline(myfile,line);

immediatly after opening the file? you are skipping the first line of the file

it is a good idea when reading data from a a file to print it out so you can check you are reading what is expected - you would probably have spotted the problem in this case

 

[horace1]

you may also have another problem

    while(myfile.good())
    {
        myfile>>x;
        n1[y]=x;
        y=y+1;

    }myfile.close();

although at the start of the loop the myfile.good() may return true the myfile>>x; statement can still fail, e.g. if the eof is reached

because the overloaded operator<<() function returns the ostream& as the function result you can test this to the if the << operation worked, e.g.

   while(myfile>>x)
    {
         n1[y]=x;
        y=y+1;
        cout << " y " << y << " data " << n1[y-1] << endl;
    }
    myfile.close();

if the myfile>>x fails it retuns a false and the while() exits

 

[horace1]

the above post #3 should have talked about the overloaded operator>>() (not operator<<() ) returning the istream& which is then tested to see if the input operation is sucessful
i.e. the function prototype looks like

std::istream& operator>>(std::istream& is, T& obj)