Why can't I overload of iostream operator?

Code:

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#include <iostream>
#include <iomanip>

using namespace std;

class PhoneNumber {
        friend ostream &operator>>(ostream &, const PhoneNumber &);
        friend istream &operator<<(istream &, const 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, const 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 phone number in the form (123) 456-7890:\n";
        cin >> phone;
        cout << "The phone number entered was: " << phone << endl;
        return 0;
}

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many many wrong message was appearing......

Code:

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mathsniper:~# g++ -o overload overload.cpp
overload.cpp: In function ‘std::ostream& operator<<(std::ostream&, const PhoneNumber&)’:
overload.cpp:10: error: ‘char PhoneNumber::areaCode [4]’ is private
overload.cpp:17: error: within this context
overload.cpp:11: error: ‘char PhoneNumber::exchange [4]’ is private
overload.cpp:18: error: within this context
overload.cpp:12: error: ‘char PhoneNumber::line [5]’ is private
overload.cpp:18: error: within this context
overload.cpp: In function ‘std::istream& operator>>(std::istream&, const PhoneNumber&)’:
overload.cpp:10: error: ‘char PhoneNumber::areaCode [4]’ is private
overload.cpp:25: error: within this context
overload.cpp:25: error: ambiguous overload for ‘operator>>’ in ‘std::operator>> [with _CharT = char, _Traits = std::char_traits<char>](((std::basic_istream<char, std::char_traits<char> ...........................................

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Could anyone tell me was wrong with the code?

It should be:

Code:

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friend ostream &operator<<(ostream &, const PhoneNumber &);
friend istream &operator>>(istream &, PhoneNumber &);

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Thanks. I have corrected it. But the wrong message is still appearing.

Code:

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mathsniper:~# g++ -o overload overload.cpp
overload.cpp: In function ‘std::istream& operator>>(std::istream&, const PhoneNumber&)’:
overload.cpp:25: error: ambiguous overload for ‘operator>>’ in ‘std::operator>> [with _CharT = char, _Traits = std::char_traits<char>](((std::basic_istream<char, std::char_traits<char> >&)(+ input)), std::setw(4)) >> num->PhoneNumber::areaCode’
/usr/lib/gcc/i486-linux-gnu/4.0.3/../../../../include/c++/4.0.3/istream:734: note: candidates are: std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*) [with _Traits = std::char_traits<char>] <near match>
...........................

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Thanks. I have corrected it. :)