迭代器

返回指向起始的迭代器

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

 
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() 。

 返回指向末尾的迭代器

std::basic_string<CharT,Traits,Allocator>::end
std::basic_string<CharT,Traits,Allocator>::cend

iterator end();                         (C++11 前) 
 
iterator end() noexcept;                (C++11 起) 
 
const_iterator end() const;             (C++11 前) 
 
const_iterator end() const noexcept;    (C++11 起) 
 
const_iterator cend() const noexcept;   (C++11 起) 

返回指向后随字符串末字符的字符的迭代器。此字符表现为占位符，试图访问它导致未定义行为。

参数                                        （无）

返回值                                        指向后随尾字符的字符的迭代器

复杂度                                        常数

返回指向起始的逆向迭代器

std::basic_string<CharT,Traits,Allocator>::rbegin
std::basic_string<CharT,Traits,Allocator>::crbegin

reverse_iterator rbegin();                                 (C++11 前) 
 
reverse_iterator rbegin() noexcept;                        (C++11 起) 
 
const_reverse_iterator rbegin() const;                     (C++11 前) 
 
const_reverse_iterator rbegin() const noexcept;            (C++11 起) 
 
const_reverse_iterator crbegin() const noexcept;           (C++11 起) 

返回指向逆转字符串首字符的逆向迭代器。它对应非逆向字符串的末字符。

 参数                             （无）

返回值                           指向首字符的逆向迭代器

复杂度                          常数

返回指向末尾的逆向迭代器

std::basic_string<CharT,Traits,Allocator>::rend
std::basic_string<CharT,Traits,Allocator>::crend

reverse_iterator rend();                    (C++11 前) 
 
reverse_iterator rend() noexcept;           (C++11 起) 
 
const_reverse_iterator rend() const;        (C++11 前) 
 
const_reverse_iterator rend() const noexcept; (C++11 起) 
 
const_reverse_iterator crend() const noexcept; (C++11 起) 

返回指向后随逆向字符串末字符的字符的逆向迭代器。它对应前驱非逆向字符串首字符的字符。此字符表现为占位符，试图访问它会导致未定义行为。

参数                     （无）

返回值                    指向后随末字符的字符的逆向迭代器

复杂度                   常数

 代码示例

    string str = "abcdefg hijk";
    // 通过const_iterator迭代器顺序遍历string
    std::cout << "const_iterator: " << std::endl;
    for (string::const_iterator it = str.cbegin(); it != str.cend(); it++)
    {
        std::cout << *it << " " ;
    }
    std::cout << std::endl;
 
    // 通过iterator迭代器顺序修改string
    std::cout << "iterator: " << std::endl;
    for (string::iterator it = str.begin(); it != str.end(); it++)
    {
        *it += 3;
    }
    std::cout << str << std::endl;
 
    // 通过const_reverse_iterator迭代器逆序遍历string
    std::cout << "const_reverse_iterator: " << std::endl;
    for (string::const_reverse_iterator it = str.crbegin(); it != str.crend(); it++)
    {
        std::cout << *it << " " ;
    }
    std::cout << std::endl;
 
    // 通过reverse_iterator迭代器逆序修改string
    std::cout << "reverse_iterator: " << std::endl;
    for (string::reverse_iterator it = str.rbegin(); it != str.rend(); it++)
    {
        *it += 3;
    }
    std::cout << str << std::endl;