segmentation fault (core dumped) reading line into array - c++

Question

I'm trying to read in a file into an array so that I could process the array into selection sort. But when I try to read in the file, I get a segmentation fault(core dumped) error. Here is my code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
string array[40707];
int loop = 0;
int loop2;
string line;
ifstream inFile("beowulf.txt");
if (inFile.is_open())
{
while(!inFile.eof())
{
getline(inFile, line);
array[loop] = line;
loop++;
}
inFile.close();
}
else cout << "Unable to open file" << endl;
for (loop2 =0; loop2 <= loop; loop2++)
cout << array[loop2] << endl;
return 0;
}

Answer 1

Change your string array to:
std::vector<std::string> array;
Then you can read the file and copy into the vector simply as:
std::copy(std::istream_iterator<std::string>(inFile),
std::istream_iterator<std::string>(),
std::back_inserter(array));
EDIT: To read the file line-by-line, either define your own insert_iterator or do it like this:
std::string line;
while (getline(inFile, line))
array.push_back(line);
Your code will then change to something like this
#include <bits/stdc++.h>
using namespace std;
int main() {
vector<string> array;
string line;
ifstream inFile("beowulf.txt");
if (!inFile.is_open()) {
cerr << "Unable to open file" << endl;
return 1;
}
while (getline(inFile, line))
array.push_back(line);
inFile.close();
for (int i = 0; i < array.size(); ++i)
cout << array[i] << endl;
return 0;
}

Answer 2

Two potential error cases I can see right away.
Overrunning the end of the end of array. It can happen while reading because there is no guard on loop. If the array read was exactly 40707 lines it will happen while printing out when loop2 == loop. Either of these is probably the cause of the segfault. The recommended solution is to use C++'s std::vector because it will dynamically size itself to the input and automate iterating through the items stored.
The second error is less severe, but allows an infinite loop on an IO error. The end of file may never be reached if an error prevents reading a line and places the stream in an error condition. Unlikely to happen with getline, but a common occurrence with formatted reads.
Using most of the OP's solution:
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;
int main()
{
vector<string> array; // vector eliminates buffer overflow problem of string array.
//int loop = 0; vector also eliminates the need for this counter
//int loop2; and this one
string line;
ifstream inFile("beowulf.txt");
if (inFile.is_open())
{
while(getline(inFile, line)) //exits if anything goes wrong with the file IO
{
array.push_back(line); // stores line in vector
}
inFile.close();
}
else cout << "Unable to open file" << endl;
// C++11 way
for (string const & str: array)
{ // iterates through the string automatically
cout << str << endl;
}
/* Old C++ way
for (vector<string>::iterator str = array.begin();
token != array.end();
++token)
{ // iterates through the string manually
cout << *str << endl;
}
*/
return 0;
}