Help reading obscure (to me) piece of code

[johnR]

I'm trying to debug a C++ program that I use (but didn't write). I can read plain C reasonably well but the C++ syntax below has me stumped:

pbuf [ j ].min *= gain;

i is an int, gain is a float and min is part of std::min. The part I'm not familiar with is the array subscript operator immediately followed by the '.' operator, ie. '[ j ].min'. If someone could explain what that means I'd appreciate it.

If more context is required, the full file is here:
https://github.com/original-male/non/blob/master/timeline/src/Waveform.C
The above code appears at line 50.

[Chervil]

pbuf is a pointer to an array of objects of type Peak.
min and max here are member variables of the Peak class/struct. Most likely they are of type float.

Those two float variables have their existing value multiplied by the scale factor gain.

The for-loop at line 48 to 52 does that same scaling for all the objects in the array.

In the context of a WAV file, it seems the array contains a series of min and max peak values (indicating the top and bottom of the waveform).

In that particular part of the code it does not seem that std::min has any relevance. To get the context of min and max, you'd need to view the header which contains the definition of Peak.
https://github.com/original-male/non/blob/master/timeline/src/Engine/Peak.H

[koothkeeper]

The definition of pbuf (class Peak) is in Engine/Peak.h. The pbuf[ j ].min is syntax pointing to the "jth" offset of the array of Peak objects. In particular:

pbuf[ j ].min *= gain;

is multiplying the min variable of the "jth" object by gain and assigning the result back to min.

Does that help?

[johnR]

Thanks for the replies. They answer my question perfectly. (Now feeling a little stupid as I should have realised 'min' had nothing to do with std::min).