Undefined Behaviour

#	Name	What happens	Fix
☠	Signed overflow	INT_MAX + 1 — compiler may remove checks	use unsigned or check before
☠	Strict aliasing	*(uint32_t*)&float_var — wrong value at -O2	use memcpy() or union
☠	No sequence point	printf("%d %d", *p++, *p++) — anything goes	one *p++ per statement
☠	Null deref before check	*p = 42; if(p==NULL) — branch eliminated	check before deref

// ; is a sequence point — side effects committed before next statement
printf("%d ", *p++);   // ok — p++ committed after ;
printf("%d ", *p++);   // ok — p already advanced
printf("%d\n", *p);    // ok — no modification