关于ostringstream的.operator<<()出错问题

[jacky_qiu]

#include<iostream>
#include <Windows.h>
#include <sstream>
#include <tchar.h>
#include <string>
using namespace std;

void main()
{
	//这样得到的结果是错误的。
	//输出的是一个地址，而不是字符串
	ostringstream test;
	test.operator<<("this is a test string");
	cout<<( std::string(test.str()).c_str() )<<endl;

	//这样就正确
	ostringstream test2;
	test2<<("this is a test string");
	cout<<( std::string(test2.str()).c_str() )<<endl;
/*

	//想请问为什么直接使用<<  和 使用 .operator<<() 会得到
	//不同的结果，因为我想继承ostringstream重载<<
	//必须调用基类的ostringstream::operator<<()方法
	但结果却出错了。希望大家给点意见，谢谢！


class Newstringstream : public std::ostringstream
{
public:
	ostringstream& operator << (POINT &point)
	{
               //这里出错了
		ostringstream::operator<<
			(_T("("))<<(point.x)<<(_T(","))<<(point.y)<<(_T(")"));
		return *this;
	}
};
	
	*/

}

[jacky_qiu]

谢谢两位！

[libinfei8848]

重载operator<<方法最好不要做成员函数，做friend。或者全局函数

ostringstream& operator << (Newstringstream &, POINT &point)

[dubiousway]

改成这样就ok:

    ostringstream test;
    operator<<(test,"this is a test string");
    cout<<( std::string(test.str()).c_str() )<<endl;

我查了一下，和字符串输出相关的重载operator<<，都是两个参数的全局函数，而不是成员函数。
所以如果你输入一个参数（当成员函数来调用，那么就只能被当作字符串地址输出了）

ostream& operator<< (bool& val );
ostream& operator<< (short& val );
ostream& operator<< (unsigned short& val );
ostream& operator<< (int& val );
ostream& operator<< (unsigned int& val );
ostream& operator<< (long& val );
ostream& operator<< (unsigned long& val );
ostream& operator<< (float& val );
ostream& operator<< (double& val );
ostream& operator<< (long double& val );
ostream& operator<< (const void* val );
 
ostream& operator<< (streambuf* sb );
 
ostream& operator<< (ostream& ( *pf )(ostream&));
ostream& operator<< (ios& ( *pf )(ios&));
ostream& operator<< (ios_base& ( *pf )(ios_base&));
 
*** the following functions are not members but GLOBAL functions:
//下面才是输出字符串相关的函数： 
ostream& operator<< (ostream& out, char c );
ostream& operator<< (ostream& out, signed char c );
ostream& operator<< (ostream& out, unsigned char c );
 
ostream& operator<< (ostream& out, const char* s );
ostream& operator<< (ostream& out, const signed char* s );
ostream& operator<< (ostream& out, const unsigned char* s );