Error using cout in conjunction with a class method

[droors]

During compilation, I get a slew of errors whenever I perform
this operation:

cout << aMatrix.Transpose( ) << endl;
 

-- the overloaded operator<< non-member method is:

       ostream & operator<<( ostream & out, const Matrix & matrixRHS )
 

-- the member method Transpose( ) [ transposes the calling object by
moving values into a temp Matrix object and then assignin it to the
calling object] is:

     void Transpose( void );
 

-- errors: [including quite a few more it won't let me post but they all
deal with the << operator]

Test.cpp:32: error: no match for ‘operator<<’ in ‘std::cout << aMatrix. Matrix::Transpose()’
/usr/lib/gcc/i486-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/ostream.tcc:67: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/lib/gcc/i486-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/ostream.tcc:78: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ios<_CharT, _Traits>& (*)(std::basic_ios<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/lib/gcc/i486-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/ostream.tcc:90: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/lib/gcc/i486-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/ostream.tcc:125: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char, _Traits = std::char_traits<char>]
 

However, the code functions correctly with this set of commands:

aMatrix.Transpose( ) ;
cout << aMatrix << endl;
 

Does anyone have any idea as to why the first method produces so many errors concerning the ostream << operator? I thought it may have something to do with the const-ness of the method but I am not allowed to change the Transpose( ) method so that it returns a const Matrix object. Anybody have any input?

[Banfa]

As well as the normal operations available you have added an overload for the cout << operator to accept a const Matrix &.

However the Transpose function is defined as

void Matrix::Transpose( void );

so in this line of code

cout << aMatrix.Transpose( ) << endl;

you are passing the type void to cout <<. Since there is no override for void an(or several) error ensues.

However in this code

aMatrix.Transpose( )
cout << aMatrix << endl;

You call the tranpose function and then pass the matrix to cout << and it can use the overloaded operator you have defined.