Question

I have tried to use the following snippet of code:

int main()
{
string location_file ("test.txt");
string data;

ifstream file (location_file);
getline (file, data);
file.close();

cout << data;
return 0;
}

But it won’t work. Now, if I were to use “ifstream file (“test.txt”)” it would. Why? Isn’t it the same thing in the end?

Answer 1

The problem is that ifstream‘s constructor does not accept a string as parameter, but only a char const*. Now "test.txt" is of type char const[9] which decays into char const* according to type promotion rules, therefore it works. However, there’s no implicit conversion from string to char const*, therefore your code doesn’t work.

To fix your code, construct your stream with:

ifstream file(location_file.c_str());