Is the default mode of ofstream implementation defined?

Question

Given the following code:

std::ofstream stream(\"somefile\");

if (!stream)
{
   return 1;
}

When invoking .write(....) and using

Answer 1

When I run your code on windows using g++ and libstdc++, i get the following result:

expect: 32
file size: 33

So the problem is not compiler specific, but rather OS specific.

While C++ uses a single character \n to represent a line ending in a string, Windows uses two bytes 0x0D and 0x0A for a line ending in a file. This means that if you write a string into a file in text mode, all occurrences of the single character \n are written using those two bytes. That's why you get additional bytes in the file size of your examples.