ostringstream/istringstream/stringstream的用法

参考链接：http://www.cnblogs.com/kex1n/archive/2011/11/06/2237934.html

1，ostringstream常用来将多个信息快速拼装进字符串string中
用法示例：

#include <iostream>
#include <sstream>

int main(void)
{
    std::string name("zeta");
    int age = 27;
    std::ostringstream os;
    os << "name: " << name << " age: " << age << std::endl;

    std::string key = os.str();
    std::cout << os.str() << std::endl;

    return 0;
}

2，istringstream常用来从string中解析需要的元素（默认这些元素以空格和回车键作为分隔符）
用法示例：

#include <iostream>
#include <sstream>

int main(void)
{
    std::string name("1 2");
    
    std::istringstream is(name);

    int num1,num2;
    is >> num1;
    is >> num2;
    std::cout << "num1: " << num1 << " num2: " << num2 << std::endl;

    return 0;
}

备注：
istringstream不能指定分隔符，若想使用其他分隔符，可使用istringstream::get函数

参考链接：http://topic.youkuaiyun.com/u/20110504/15/2bbbbc76-6e9c-45bb-924c-b03da819407c.html

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

int main()
{
    int length ;
    std::string st = "Enter,the,name,of,an,existing,text,file:";
    std::istringstream stream(st);
    int i = 0;
    char array[20] = {0};
    while(stream.get(array, 20, ','))
    {
        //获取当前位置
        length = stream.tellg();

        std::cout << array << std::endl;

        //跳过逗号（,）
        stream.seekg (length + 1, std::ios::beg);
    }

    return 0;
}

 执行效果如下图所示：

3，stringstream常用来实现数据转换

用法示例：

#include <iostream>
#include <sstream>

int main(void)
{
    std::stringstream ss;

    ss << "123";

    int num1;
    ss >> num1;
    std::cout << "num1: " << num1 << std::endl;

    ss.clear();

    ss << "245";

    int num2;
    ss >> num2;
    std::cout << "num2: " << num2 << std::endl;
 
    return 0;
}