Question

I am having problems with the following code. What I expect is for the do-while loop to execute 4 times, once for each line of the text file it is reading in, but in reality is it executing five time, which is resulting in a segfault later in the program. What am I doing wrong here that’s causing it to execute the extra iteration? I’ve tried replacing he do-while with a simple while loop but the result is the same.

int count = 0;
string devices[4];
string line;
ifstream DeviceList;
DeviceList.open("devices/device_list.txt");
do
{
 getline(DeviceList, line);
 devices[count] = line;
 count ++;
} while(!DeviceList.eof());

device_list.txt contains the following:

WirelessAdaptor
GPU
CPU
Display

Answer 1

eof() doesn’t return true until getline consumes the end. It doesn’t do this until the getline call after reading the last line. You need to check if eof is true immediately after your getline call:

while(true)
{
  getline(DeviceList, line);
  if(DeviceList.eof())
    break;
}