answer - Undefiened behaviour
AT certain specified points in the execution sequence called sequence points, all side effects of previous evaluations are guaranteed to be complete. A sequence point defines any point in a computer program’s execution at which it is guaranteed that all side effects of previous evaluations will have been performed, and no side effects from subsequent evaluations have yet been performed. Following are the sequence points listed in the C standard:
— The end of the first operand of the following operators:
a) logical AND &&
b) logical OR ||
c) conditional ?
d) comma ,