Operation on … may be undefined?

Question

I have the following code

FRAME frameArray[5][10]; // Create the array of frames
int trackBufferFull[5] = {0, 0, 0, 0, 0};// Keeps track of how full the buffer f         


        

Answer 1

You're modifying trackTail[nodeNumber - 1] between sequence points. It's like you're assigning

i = ++i;

which is also undefined behaviour.

Change your code to something like this:

trackTail[nodeNumber - 1] = (trackTail[nodeNumber - 1] + 1) % 10;