C++中sstream

sstream中有三个常用的类： 1. stringstream(同时支持>> 和<<) 2. istringstream(只支持>>) 3. ostringstream(只支持<<)

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#include <string>
#include <sstream>//
#include <iostream>
using namespace std;
//ostringstream 用于执行C风格字符串的输出操作
void ostringstream_test()
{
    //ostringstream 只支持 << 操作符
    std::ostringstream oss;
    oss << "this is test" << 123456;
    std::cout<<oss.str()<<std::endl;
    oss.str("");//清空之前的内容
    //oss.clear();//并不能清空内存
    //浮点数转换限制
    double tmp = 123.1234567890123;
    oss.precision(12);
    oss.setf(std::ios::fixed);//将浮点数的位数限定为小数点之后的位数
    oss << tmp;

    std::cout << oss.str() << "\r\n" << std::endl;
}

//istringstream 用于执行C风格字符串的输入操作
void istringstream_test()
{
    //istringstream 只支持 >> 操作符
    std::string str = "welcome to china";
    std::istringstream iss(str);

    //把字符串中以空格隔开的内容提取出来
    std::string out;
    while(iss >> out)
    {
        std::cout << out << std::endl;
    }
    std::cout << "\r\n" << std::endl;
}

//stringstream 同时支持C风格字符串的输入输出操作
void stringstream_test()
{
    //输入
    std::stringstream ss;
    ss << "hello this is kandy " << 123;
    std::cout << ss.str() << "\r\n" << std::endl;

    //输出
    std::string out;
    while(ss >> out)
    {
        std::cout << out.c_str() << std::endl;
    }
    std::cout << "\r\n" << std::endl;
}

int main()
{
    ostringstream_test();   
    istringstream_test();
    stringstream_test();
    system("pause");
    return 0;
}