The program compiles without errors with mingw32 egcs 2.91.60.

However, your dummy string declaration needs a semicolon. Make sure the rest
of your code is what you are having trouble with.
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I encountered a problem while building a test stub for a matrix class that I
am working on. When I compile the code below with Visual C++ 5.0 (SP3), I get
the following compile time error (don't you just love these STL errors?) :

C:\DevTools\DevStudio\VC\INCLUDE\vector(36) :  error C2440: 'default
argument' : cannot convert from 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char>

>' to 'const class std::allocator<char> &'
   Reason: cannot convert from 'class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> >' to 'const class
std::allocator<char>'
   No user-defined-conversion operator available that can perform this
conversion, or the operator cannot be called

However, if I create a dummy string variable the error goes away. I would
certainly not categorize myself as an template expert (in fact I usually
cringe when I look at some of the STL documentation) so this could just be a
feature of the STL. Unfortunately, I don't have any other compilers to try
this out on. What do the C++ experts say?

Regards,

Jeremy Jameson
Micromedex, Inc.

//-------------------------------------------------------------------------
#include <vector>
#include <string>

template <class T>
class matrix
{
private:
 typedef std::vector<T> matrix_type;

public:
 typedef matrix_type::value_type value_type;
 typedef matrix_type::reference reference;
 typedef matrix_type::const_reference const_reference;
 typedef matrix_type::size_type size_type;

private:
 size_type m_nRows, m_nColumns;
 matrix_type m_Matrix;

public:
 matrix( size_type rows, size_type columns ) :
   m_nRows( rows ), m_nColumns( columns ),
   m_Matrix( rows * columns )
 {

 }

 size_type rows( ) const { return m_nRows; }
 size_type columns( ) const { return m_nColumns; }

 reference operator( ) ( size_type row, size_type column )
 {
  return m_Matrix[row * m_nColumns + column];
 }

 const_reference operator( ) ( size_type row, size_type column ) const
 {
  return m_Matrix[row * m_nColumns + column];
 }
};

int main( )
{
 // Uncomment the following line to workaround the C2440 compile error.
 //std::string Work_Around_for_C2440_Compile_Error

 matrix<std::string> Matrix( 2, 2 );

 Matrix( 0, 0 ) = "(0,0)";
 Matrix( 0, 1 ) = "(0,1)";
 Matrix( 1, 0 ) = "(1,0)";
 Matrix( 1, 1 ) = "(1,1)";

 return( 0 );
}

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