Yes, semantically it will be evaluated on every loop. In some cases, compilers may be able to remove the condition from the loop automatically – but not always. In particular: void foo(const struct rect *r) { for (int i = 0; i < r->width * r->height; i++) { quux(); } } The compiler will not … Read more
Interesting question. So, what’s going to happened ? Well if you debug with gdb you’ll see something like 3 member variables (names are not accurate): _M_begin: pointer to the first element of the dynamic array _M_end: pointer one past the last element of the dynamic array _M_capacity: pointer one past the last element that could … Read more
In theory, it is called each time, since a for loop: for(initialization; condition; increment) body; is expanded to something like { initialization; while(condition) { body; increment; } } (notice the curly braces, because initialization is already in an inner scope) In practice, if the compiler understands that a piece of your condition is invariant through … Read more
LINEAR-SEARCH(A, ν) 1 for i = 1 to A.length 2 if A[i] == ν 3 return i 4 return NIL Loop invariant: at the start of the ith iteration of the for loop (lines 1–4), ∀ k ∈ [1, i) A[k] ≠ ν. Initialization: i == 1 ⟹ [1, i) == Ø ⟹ ∀ k … Read more
In simple words, a loop invariant is some predicate (condition) that holds for every iteration of the loop. For example, let’s look at a simple for loop that looks like this: int j = 9; for(int i=0; i<10; i++) j–; In this example it is true (for every iteration) that i + j == 9. … Read more