Example of Why stream::good is Wrong?

Question

I gave an answer which I wanted to check the validity of stream each time through a loop here.

My original code used good and looked similar to this:

Answer 1

both good() and eof() will both give you an extra line in your code. If you have a blank file and run this:

std::ifstream foo1("foo1.txt");
std::string line;
int lineNum = 1;

std::cout << "foo1.txt Controlled With good():\n";
while (foo1.good())
{
    std::getline(foo1, line);
    std::cout << lineNum++ << line << std::endl;
}
foo1.close();
foo1.open("foo1.txt");
lineNum = 1;

std::cout << "\n\nfoo1.txt Controlled With getline():\n";
while (std::getline(foo1, line))
{
    std::cout << line << std::endl;
}

The output you will get is

foo1.txt Controlled With good():
1

foo1.txt Controlled With getline():

This proves that it isn't working correctly since a blank file should never be read. The only way to know that is to use a read condition since the stream will always be good the first time it reads.