So I was given the assignment that asks user to enter file name, then the program will read all integers from the file (unknown number of integers) to an array, and display highest, lowest number, average and number of integers read.
The only problem that I have with this is right at the beginning. To check whether user enters a correct file name, I use a while loop. But it turned out that even if user enters a correct file name at the second time (given the first time he fails), he still cannot quit the loop.
Any idea where the bug is?

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

int main()
{
    const int SIZE = 400;
    int actual_size = 0, number[SIZE], highest, lowest, sum;
    double average;;
    ifstream inputfile;
    string file_name;   

    cout << "Please enter a file name: ";
    cin >> file_name; // get file name from user
    inputfile.open(file_name.c_str()); // open file, using the file name user entered

    // check if opening file succeeds. if not ask user to submit a right name
    while (!(inputfile))
    {
        cout << "\nError. Please enter a correct file name: ";
        cin >> file_name;
        inputfile.open(file_name.c_str());
    } // end while-statement

    // read inputfile into array number - actual_size = 0 at the beginning
    while (inputfile >> number[actual_size])
            actual_size++;
    // end while-statement

    // find lowest and highest number, and sum
    sum = number[0];
    lowest = number[0];
    highest = number[0];
    for (int index = 1; index < actual_size; index++)
    {
        sum += number[index];
        if (number[index] >= highest)
            highest = number[index];
        if (number[index] <= lowest)
            lowest = number[index];
    } // end for-statement. 

    average = 1.0 * sum / actual_size; // calculating average

    cout << fixed << showpoint << setprecision(2);
    cout << "The highest number is: " << highest
         << "\nThe lowest number is: " << lowest
         << "\nThe total of the numbers in the array is: " << actual_size
         << "\nThe average of the numbers in the array is: " << average << endl;
     return 0;

} // end function main 

This is the file that I used "test.txt"
100
200
300
400
50
60
0
80
90
350

The code above works fine for me in Visual C++ 2010.

You might try a infile.clear( ); before you attempt to open the file again inside the loop.

Yeah.. that might be a problem since I'm using the version 2008...
Yup, it works now, with .clear() :). Thanks!

Yup, it works now, with .clear() :). Thanks!

As a side note, the reason for that is the status flags of a file stream object are independent of the file that it points to. So if you open a file successfully, read it to EOF, then close it, attempting to open another file and read from it using the same stream object wouldn't work because the eofbit would still be set for the object.

As another example, your specific problem is that the open() member function failed on an invalid file name. This sets the failbit, which remains set even when you try to open a valid file name.

Calling the clear() member function clears the status bits.

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