std::vector<T,Allocator>::begin, std::vector<T,Allocator>::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.

Notes

libc++ backports cbegin() to C++98 mode.

[edit] Example

#include #include #include #include #include   int main() { std::vector nums{1, 2, 4, 8, 16}; std::vector<std::string> fruits{"orange", "apple", "raspberry"}; std::vector empty;   // Print vector. std::for_each(nums.begin(), nums.end(), [](const int n) { std::cout << n << ' '; }); std::cout << '\n';   // Sums all integers in the vector nums (if any), printing only the result. std::cout << "Sum of nums: " << std::accumulate(nums.begin(), nums.end(), 0) << '\n';   // Prints the first fruit in the vector fruits, checking if there is any. if (!fruits.empty()) std::cout << "First fruit: " << *fruits.begin() << '\n';   if (empty.begin() == empty.end()) std::cout << "vector 'empty' is indeed empty.\n"; }

Output:

1 2 4 8 16 Sum of nums: 31 First fruit: orange vector 'empty' is indeed empty.

[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] |