Why does (!file.eof()) cause repeat of last input
The last line of input doubles in output in the Bloodshed Dev-C++ compiler.
The input file is (employee.txt):
7453 40 18.00
1049 38 32.00
6734 39 22.00
4545 40 24.00
9707 38 35.00
The input file is (employee.txt):
7453 40 18.00
1049 38 32.00
6734 39 22.00
4545 40 24.00
9707 38 35.00
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
int numberofemployees;
int employeeid, hoursworked;
float hourlyrate, grosspay, taxamount, netpay;
const float TAXRATE=0.10;
std::ifstream fin("employee.txt");
while (!fin.eof() )
{
fin >> employeeid >>hoursworked >> hourlyrate;
std::cout<<"THE EMPLOYEE ID IS: "<<employeeid<<endl;
std::cout<<"THE HOURS WORKED ARE: "<<hoursworked<<endl;
std::cout<<"THE HOURLY RATE IS: "<<hourlyrate<<endl;
grosspay=hoursworked*hourlyrate;
taxamount=grosspay*TAXRATE;
netpay=grosspay-taxamount;
std::cout<<"THE GROSSPAY IS: "<<grosspay<<endl;
std::cout<<"THE TAX MOUNT IS: "<<taxamount<<endl;
std::cout<<"THE NETPAY IS: "<<netpay<<endl;
}
fin.close ();
getchar ();
return 0;
}//MAIN
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vhpgomes
A little typo... of course the condition of the while should be while(!fin.eof() && !fin.fail()) ... forgot the '!'
The EOF condition is only met when you try to read PAST the end of the file. As long as you don't read past the end of the file, fin.eof() will not be true.
So, after processing the last data, the loop will start again (since fin.eof() is not true yet), and the read operation :
fin >> employeeid >>hoursworked >> hourlyrate;
will try to read past the end of the file. This will make fin.eof() true, and moreover, reading the values will not succeed (since there aren't any to be read). Your code will happily print the last record again.
In other words, you need to check fin.eof() AFTER you tried to read from the file.
Or better yet, use getline to read the file one line at a time :
So, after processing the last data, the loop will start again (since fin.eof() is not true yet), and the read operation :
fin >> employeeid >>hoursworked >> hourlyrate;
will try to read past the end of the file. This will make fin.eof() true, and moreover, reading the values will not succeed (since there aren't any to be read). Your code will happily print the last record again.
In other words, you need to check fin.eof() AFTER you tried to read from the file.
Or better yet, use getline to read the file one line at a time :
std::string line;
while (getline(fin, line)) {
// do something with 'line'. You could for example use a stringstream to extract the values from it
}
C++
C++ is an intermediate-level general-purpose programming language, not to be confused with C or C#. It was developed as a set of extensions to the C programming language to improve type-safety and add support for automatic resource management, object-orientation, generic programming, and exception handling, among other features.
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