C++: Write to an existing file? [duplicate]

Question

In C++, I need to write to an existing file and keep the previous content there.

This is what I have done:

std::ofstream logging;

logging.open(FILENAME);

logging << "HELLO\n";

logging.close();

but then my previous text is overwritten (gone). What did I do wrong?

Thanks in advance.

Answer 1

logging.open(FILENAME, std::ios_base::app); 

Answer 2

You have to open the file in append mode:

logging.open(FILENAME, std::ios::app);