《C++大学教程》中关于运算符重载的一个例程

[rabbitjerry]

《C++大学教程（第二版）》第八章关于"<<"和">>"的重载的实例如下：

#include <iostream>
#include <iomanip>

class PhoneNumber{
	friend ostream &operator<<(ostream&, const PhoneNumber&);
	friend istream &operator>>(istream &, PhoneNumber &);
private:
	char areaCode[4];
	char exchange[4];
	char line[5];
};
ostream &operator<<(ostream &output,const PhoneNumber & num)
{
	output << "(" << num.areaCode <<") "
		<< num.exchange << "-" << num.line;
	return output;
}
istream &operator>>(istream &input, PhoneNumber & num)
{
	input.ignore();
	input >> setw(4) >>num.areaCode;
	input.ignore(2);
	input >> setw(4) >> num.exchange;
	input.ignore();
	input >> setw(5) >> num.line;
	return input;
}

int main()
{
	PhoneNumber phone;
	cout << "Enter a phone number in the form of (123) 456-789:\n";
	cin >> phone;
	cout << "The phone number entered was: " << phone <<endl;
	return 0;
}

上述代码中，除了注释没有copy过来，以及#include <iostream>和#include <iomanip>中没有加“.h”标示，其余都一样。
如果加了.h标示，则会报错说找不到文件。
然而把.h标示去掉后，报了27个错误：

1>fig08_03.cpp
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(5) : error C2143: syntax error : missing ';' before '&'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(5) : error C2433: 'ostream' : 'friend' not permitted on data declarations
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(5) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(5) : error C2061: syntax error : identifier 'ostream'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(5) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(5) : error C2805: binary 'operator <<' has too few parameters
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(6) : error C2143: syntax error : missing ';' before '&'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(6) : error C2433: 'istream' : 'friend' not permitted on data declarations
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(6) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(6) : error C2061: syntax error : identifier 'istream'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(6) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(6) : error C2805: binary 'operator >>' has too few parameters
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(12) : error C2143: syntax error : missing ';' before '&'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(12) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(12) : error C2086: 'int ostream' : redefinition
1>        d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(5) : see declaration of 'ostream'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(12) : error C2065: 'output' : undeclared identifier
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(12) : error C2059: syntax error : 'const'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(13) : error C2143: syntax error : missing ';' before '{'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(13) : error C2447: '{' : missing function header (old-style formal list?)
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : error C2143: syntax error : missing ';' before '&'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : error C2086: 'int istream' : redefinition
1>        d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(6) : see declaration of 'istream'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : error C2065: 'input' : undeclared identifier
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : error C2065: 'num' : undeclared identifier
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : error C2275: 'PhoneNumber' : illegal use of this type as an expression
1>        d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(4) : see declaration of 'PhoneNumber'
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\myc++study\fig08_03\fig08_03\fig08_03.cpp(18) : fatal error C1903: unable to recover from previous error(s); stopping compilation
1>Build log was saved at "file://d:\myC++Study\fig08_03\fig08_03\Debug\BuildLog.htm"
1>fig08_03 - 27 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

我想这不是代码敲错了，应该是设置哪儿有问题吧。
环境是VS2005，默认安装的，没有做过设置方面的修改。之前跑过简单的C++程序也成功了。
请高手帮忙！！！

[無_1024]

加一个using namespace std;

[無_1024]

#include <iostream>
#include <iomanip>

using namespace std;

class PhoneNumber{
    friend ostream &operator<<(ostream&, const PhoneNumber&);
    friend istream &operator>>(istream &, PhoneNumber &);
private:
    char areaCode[4];
    char exchange[4];
    char line[5];
};
ostream &operator<<(ostream &output,const PhoneNumber & num)
{
    output << "(" << num.areaCode <<") "
        << num.exchange << "-" << num.line;
    return output;
}
istream &operator>>(istream &input, PhoneNumber & num)
{
    input.ignore();
    input >> setw(4) >>num.areaCode;
    input.ignore(2);
    input >> setw(4) >> num.exchange;
    input.ignore();
    input >> setw(5) >> num.line;
    return input;
}

int main()
{
    PhoneNumber phone;
    cout << "Enter a phone number in the form of (123) 456-789:\n";
    cin >> phone;
    cout << "The phone number entered was: " << phone <<endl;
    return 0;
}

//VS2010 通过

[bluesky12312388]

VS2005不支持不标准的iostream.h
必须 使用iostream
然后using namespace std;

[rabbitjerry]

谢谢楼上的三位！！！
【补充问题】
friend ostream &operator<<(ostream&, const PhoneNumber&);
输出流重载时为什么在PhoneNumber&前加const关键字？

[I_code]

[Quote=引用 4 楼 rabbitjerry 的回复:]
谢谢楼上的三位！！！
【补充问题】
friend ostream &operator<<(ostream&, const PhoneNumber&);
输出流重载时为什么在PhoneNumber&前加const关键字？
[/Quote]

使传入的参数PhoneNumber的值不能该程序中改变...

[Sou2012]

using namespace std;