Segmentation fault with array

Question

I am writing a fairly simple code to enter integers stored in a file into an array of moderate size, but on compiling and running the code, it gives Segmentation fault error, can anyone please correct me where I am making a mistake, the code is

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

using namespace std;

int main()
{
    int arr[100000];
    ifstream f;
    f.open("IntegerArray.txt");
    string line;

    if (f.is_open())
    {
        int i=0;
        while (f.good())
        {
            getline(f,line);
            arr[i++] = atoi(line.c_str());
        }
        f.close();
    }
    else
        cout<<"file not open";
    return 0;
}

I think you have more than 100000 lines in your IntegerArray.txt. — marktani, Jun 22 '12 at 22:53
[Do not read while(good)](http://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-considered-wrong). (The question title mentions eof(), but the same reasoning applies) — R. Martinho Fernandes, Jun 22 '12 at 22:54
correct. You need to check for every read whether you had any read error. — deebee, Jun 22 '12 at 22:57
Use a `std::vector` instead of your raw array. If you know it's going to be exactly 100000, then `std::array` would be a bit better if you can use it. — chris, Jun 22 '12 at 22:58
after the last read, the stream has not reached eof() and is still good(). So you need to check it right before you use the last read data! — deebee, Jun 22 '12 at 22:59
I didn't say to change it to eof(). Just read the answers to the other question I linked. — R. Martinho Fernandes, Jun 22 '12 at 23:01
@R. Martinho Fernandes, ok sorry, I misunderstood your comment, it works now, thanks — adityaarun1, Jun 22 '12 at 23:04

score 2 · Answer 1 · answered Mar 05 '17 at 21:28

After rading a line from a file with getline(), the stream should be checked for potential errors, for example with .fail(), which:

Returns true if either (or both) the failbit or the badbit error state flags is set for the stream.

while (f.good())
{
    getline(f,line);

    if (f.fail()) {
        cout << "Corrupt data" << endl; // example output
        break;
    }

    // everything ok, continue with logic
    arr[i++] = atoi(line.c_str());
}

Segmentation fault with array

1 Answers1