Thread: Why can't I overload of iostream operator?

  1. #1
    Registered User
    Join Date
    Apr 2005
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    77

    Why can't I overload of iostream operator?

    Code:
    #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;
    }
    many many wrong message was appearing......
    Code:
    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> ...........................................
    Could anyone tell me was wrong with the code?

  2. #2
    C++ Witch laserlight's Avatar
    Join Date
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    Singapore
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    28,413
    It should be:
    Code:
    friend ostream &operator<<(ostream &, const PhoneNumber &);
    friend istream &operator>>(istream &, PhoneNumber &);
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
    Registered User
    Join Date
    Apr 2005
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    77
    Thanks. I have corrected it. But the wrong message is still appearing.
    Code:
    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>
    ...........................

  4. #4
    Registered User
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    Apr 2005
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    77
    Thanks. I have corrected it.

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