std::deque::begin, std::deque::cbegin

来自cppreference.com
< cpp‎ | container‎ | deque
iterator begin();
(C++11 前)
iterator begin() noexcept;
(C++11 起)
const_iterator begin() const;
(C++11 前)
const_iterator begin() const noexcept;
(C++11 起)
const_iterator cbegin() const noexcept;
(C++11 起)

返回指向容器首元素的迭代器。

若容器为空,则返回的迭代器将等于 end()

range-begin-end.svg

目录

[编辑] 参数

(无)

[编辑] 返回值

指向首元素的迭代器

[编辑] 复杂度

常数

[编辑] 示例

#include <iostream>
#include <deque>
#include <string>
 
int main()
{
	std::deque<int> ints {1, 2, 4, 8, 16};
	std::deque<std::string> fruits {"orange", "apple", "raspberry"};
	std::deque<char> empty;
 
	// 求和 deque ints 中的所有整数(若存在),仅打印结果。
	int sum = 0;
	for (auto it = ints.cbegin(); it != ints.cend(); it++)
		sum += *it;
	std::cout << "Sum of ints: " << sum << "\n";
 
	// 打印 deque fruits 中的首个水果,而不检查是否有一个。
	std::cout << "First fruit: " << *fruits.begin() << "\n";
 
	if (empty.begin() == empty.end())
		std::cout << "deque 'empty' is indeed empty.\n";
}

输出:

Sum of ints: 31
First fruit: orange
deque 'empty' is indeed empty.

[编辑] 参阅

返回指向容器尾端的迭代器
(公开成员函数) [编辑]