std::vector<T,Allocator>::begin, std::vector<T,Allocator>::cbegin
From cppreference.com
iterator begin(); |
(until C++11) | |
iterator begin() noexcept; |
(since C++11) | |
const_iterator begin() const; |
(until C++11) | |
const_iterator begin() const noexcept; |
(since C++11) | |
const_iterator cbegin() const noexcept; |
(since C++11) | |
Returns an iterator to the first element of the container.
If the container is empty, the returned iterator will be equal to end().
Parameters
(none)
Return value
Iterator to the first element
Complexity
Constant
Example
Run this code
#include <iostream> #include <vector> #include <string> int main() { std::vector<int> ints {1, 2, 4, 8, 16}; std::vector<std::string> fruits {"orange", "apple", "raspberry"}; std::vector<char> empty; // Sums all integers in the vector ints (if any), printing only the result. int sum = 0; for (auto it = ints.cbegin(); it != ints.cend(); it++) sum += *it; std::cout << "Sum of ints: " << sum << "\n"; // Prints the first fruit in the vector fruits, without checking if there is one. std::cout << "First fruit: " << *fruits.begin() << "\n"; if (empty.begin() == empty.end()) std::cout << "vector 'empty' is indeed empty.\n"; }
Output:
Sum of ints: 31 First fruit: orange vector 'empty' is indeed empty.
See also
returns an iterator to the end (public member function) |