c++11 标准模板（STL）（std::basic_istringstream）（五）

定义于头文件 <sstream>

|-------------------------------------------------------------------------------------------------------------------------------------------|---|-----------|
| template< class CharT, class Traits = std::char_traits<CharT> > class basic_istringstream; | | (C++11 前) |
| template< class CharT, class Traits = std::char_traits<CharT>, class Allocator = std::allocator<CharT> > class basic_istringstream; | | (C++11 起) |

类模板 std::basic_istringstream 实现基于字符串的流上的输入与输出操作。它等效地存储一个 std::basic_string 的实例，并在其上进行输入操作。

在低层，该类实际上包装 std::basic_stringbuf 的未处理字符串设备到 std::basic_istream 的高层接口中。提供到独有 std::basic_stringbuf 成员的完整接口。

亦定义对于常用字符类型的二个特化：

|------------------|--------------------------------|
| 类型 | 定义 |
| istringstream | basic_istringstream<char> |
| wistringstream | basic_istringstream<wchar_t> |

非成员函数

特化 std::swap 算法

std::swap(std::basic_istringstream)

|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| template< class CharT, class Traits, class Alloc > void swap( std::basic_istringstream<CharT,Traits,Alloc>& lhs, std::basic_istringstream<CharT,Traits,Alloc>& rhs ); |

为 std::basic_istringstream 特化 std::swap 算法。交换 lhs 与 rhs 的状态。等效地调用 lhs.swap(rhs) 。

参数

|----------|---|---------|
| lhs, rhs | - | 要交换状态的流 |

返回值

（无）

异常

（无）

调用示例

#include <sstream>
#include <string>
#include <iostream>

int main()
{
    //3) 以 str 的副本为底层字符串设备的初始内容。
    std::string string1 = "I am a handsome programmer";
    std::basic_istringstream<char> basic_istringstream1(string1, std::ios_base::in);
    std::cout << "basic_istringstream1: " << basic_istringstream1.str() << std::endl;
    std::cout << "basic_istringstream1 rdstate: ";
    std::cout << basic_istringstream1.rdstate() << std::endl;

    std::string string2 = "I am a super handsome guy";
    std::basic_istringstream<char> basic_istringstream2(string2, std::ios_base::in);
    std::cout << "basic_istringstream2: " << basic_istringstream2.str() << std::endl;
    basic_istringstream2.setstate(std::ios_base::badbit);
    std::cout << "basic_istringstream2 rdstate: ";
    std::cout << basic_istringstream2.rdstate() << std::endl;
    std::cout << std::endl;

    //为 std::basic_istringstream 特化 std::swap 算法。
    //交换 lhs 与 rhs 的状态。等效地调用 lhs.swap(rhs)
    std::swap(basic_istringstream1, basic_istringstream2);
    std::cout << "after swap: " << std::endl;

    basic_istringstream1.seekg(std::ios_base::beg);
    std::cout << "basic_istringstream1: " << basic_istringstream1.str() << std::endl;
    std::cout << "basic_istringstream1 rdstate: ";
    std::cout << basic_istringstream1.rdstate() << std::endl;

    basic_istringstream2.seekg(std::ios_base::beg);
    std::cout << "basic_istringstream2: " << basic_istringstream2.str() << std::endl;
    std::cout << "basic_istringstream2 rdstate: ";
    std::cout << basic_istringstream2.rdstate() << std::endl;

    return 0;
}

输出