std::array<T,N>::begin, std::array<T,N>::cbegin - cppreference.com (original) (raw)

Returns an iterator to the first element of *this.

If *this is empty, the returned iterator will be equal to end().

[edit] Return value

Iterator to the first element.

[edit] Complexity

Constant.

[edit] Example

#include #include #include #include   int main() { std::cout << std::boolalpha;   std::array<int, 0> empty; std::cout << "1) " << (empty.begin() == empty.end()) << ' ' // true << (empty.cbegin() == empty.cend()) << '\n'; // true // *(empty.begin()) = 42; // => undefined behavior at run-time     std::array<int, 4> numbers{5, 2, 3, 4}; std::cout << "2) " << (numbers.begin() == numbers.end()) << ' ' // false << (numbers.cbegin() == numbers.cend()) << '\n' // false << "3) " << *(numbers.begin()) << ' ' // 5 << *(numbers.cbegin()) << '\n'; // 5   *numbers.begin() = 1; std::cout << "4) " << *(numbers.begin()) << '\n'; // 1 // *(numbers.cbegin()) = 42; // compile-time error: // read-only variable is not assignable   // print out all elements std::cout << "5) "; std::for_each(numbers.cbegin(), numbers.cend(), [](int x) { std::cout << x << ' '; }); std::cout << '\n';   constexpr std::array constants{'A', 'B', 'C'}; static_assert(constants.begin() != constants.end()); // OK static_assert(constants.cbegin() != constants.cend()); // OK static_assert(*constants.begin() == 'A'); // OK static_assert(*constants.cbegin() == 'A'); // OK // *constants.begin() = 'Z'; // compile-time error: // read-only variable is not assignable }

Output:

1. true true
2. false false
3. 5 5
4. 1
5. 1 2 3 4

[edit] See also

| | returns an iterator to the end (public member function) [edit] | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | returns an iterator to the beginning of a container or array (function template) [edit] |