std::basic_string<CharT,Traits,Allocator>::begin, std::basic_string<CharT,Traits,Allocator>::cbegin

 

C++

语言

标准库头文件

自立与有宿主实现

具名要求

语言支持库

概念库 (C++20)

诊断库

工具库

字符串库

容器库

迭代器库

范围库 (C++20)

算法库

数值库

本地化库

输入/输出库

文件系统库 (C++17)

正则表达式库 (C++11)

原子操作库 (C++11)

线程支持库 (C++11)

技术规范

 

字符串库

空终止字符串

字节字符串

多字节字符串

宽字符串

类

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

成员函数 basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator 元素访问 basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) 迭代器 basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) 容量 basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)   操作 basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::starts_with (C++20)   basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23) basic_string::swap

搜索 basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of 常量 basic_string::npos 推导指引 (C++17) 非成员函数 operator+ swap(std::basic_string) operator""s (C++14) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline 比较 operator==operator!=operator<operator>operator<=operator>=operator<=> (C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20) 数值转换 stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) 辅助类 hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string>hash<std::u8string> (C++11)  (C++11)(C++11)(C++11)(C++20) hash<std::pmr::string>hash<std::pmr::wstring>hash<std::pmr::u32string>hash<std::pmr::u16string>hash<std::pmr::u8string> (C++17)(C++17)(C++17)(C++17)(C++20)

 

	(1)
iterator begin();			(C++11 前)
iterator begin() noexcept;			(C++11 起) (C++20 前)
constexpr iterator begin() noexcept;			(C++20 起)
		(2)
const_iterator begin() const;				(C++11 前)
const_iterator begin() const noexcept;				(C++11 起) (C++20 前)
constexpr const_iterator begin() const noexcept;				(C++20 起)
			(3)
const_iterator cbegin() const noexcept;					(C++11 起) (C++20 前)
constexpr const_iterator cbegin() const noexcept;					(C++20 起)

返回指向字符串首字符的迭代器。

begin() 返回可变或常迭代器，取决于 *this 的常性。

cbegin() 始终返回常迭代器。它等价于 const_cast<const basic_string&>(*this).begin() 。

参数

（无）

返回值

指向首字符的迭代器

复杂度

常数

示例

运行此代码

#include <string>
#include <iostream>
 
int main()
{
    std::string s("Exemplar");
    *s.begin() = 'e';
    std::cout << s <<'\n';
 
    auto i = s.cbegin();
    std::cout << *i << '\n';
//  *i = 'E'; // 错误： i 是常迭代器
}

输出：

exemplar
e

参阅

end cend (C++11)

返回指向末尾的迭代器 (公开成员函数)