How do functions inform user that it throws exception based on function prototype?

Question

I went through several discussion, tutorials etc. and I've a feeling like there is no way to inform the user using prototype, that his function might throw an exception.

For instance:

/* AudioStream.h */
class AudioStream
{
   int open(struct stream_settings &settings);
}

/* AudioStream.cpp */
int AudioStream::open(struct stream_settings &settings)
{
    int err;
    err = snd_pcm_open(...);
    if (err < 0)
    {
        /* Throw some exception here */
    }
}

If the final product ends up in a library with a header. How does one figures out, that the open function throws an exception and it's necessary to put it into a try/catch block?

Thank you for all the great answers.

Answer 1

Unlike some languages which indicate in the function signature that it "throws", C++ has no such mechanism. This is something you must establish in the documentation or comments near the function definition.