Just ask it to find and fix the bug! I suspect bugs like this will become less common as the model is tweaked or additional compute time is given to "reflect" on the response and check for logical consistency.

Question: Would the write to substring[6] cause an error?

Answer: Yes, the write to substring[6] in the code you have provided would cause an error, because the substring array is only defined to have a length of 6, so attempting to write to the seventh element (substring[6]) would overrun the bounds of the array and result in undefined behavior.

To avoid this issue, the code could be modified to ensure that the substring array has a length of 7, so that the null-terminator character can be safely written to substring[6] without overrunning the bounds of the array. This could be done by changing the definition of the substring array to the following:

char substring[7];

Wow - thanks for pointing this out. After a few minutes I can do both techniques. Basically, one is looking beyond the image and the other is looking in front of the image. Looking beyond however seems MUCH easier as your eyes don't cross nearly as much, though.