Question

Consider the following code:

typedef std::vector<int> cont_t; // Any container with RA-iterators
typedef cont_t::const_iterator citer_t; // Random access iterator

cont_t v(100);
const int start = 15; // start > 0.
citer_t it = v.begin() - start; // Do not use *it

int a1 = 20, b1 = 30; // a1, b1 >= start
int a2 = 30, b2 = 40; // a2, b2 >= start

int x = std::min_element(it + a1, it + b1); // 
int y = std::min_element(it + a2, it + b2); //
int z = std::min_element(it + 15, it + 25); //
...

Is it possible to use the random access iterator it out of range?

Answer 1

You ll get assertion condition here according to C++ Standard 24.1.5 Table 76.

Answer 2

It s certainly possible to write code that trys to use an out-of-range iterator. Running the code will give undefined behaviour. Depending on the library implementation, it may throw an exception, access random bits of memory, trigger a protection fault, or initiate a thermonuclear explosion in your CPU.

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