Template class and class properties that are also templates

Question

I'm having trouble compiling the following header. It's my first experience with templates and I guess I'm getting something wrong. The compilers point errors at vector<vector<T>> data_; and the operator overloading function. I would like the data_ vector to have the same type as the OptBaseMatrix object but I'm not sure how to do it... I really don't know how to solve this problem. Help!

#ifndef OPTBASEMATRIX_H
#define OPTBASEMATRIX_H

#include <vector>

template<typename T>
class OptBaseMatrix 
{ 
public:
 vector<vector<T>> data_; 

 OptBaseMatrix(int rows, int cols);
 ~OptBaseMatrix();

 void readMatrix();
 void printMatrix();
 int getRows();
 int getCols();

    OptBaseMatrix<T> operator+(const OptBaseMatrix<T>& matrix1, const OptBaseMatrix<T>& matrix2);

private:
 int rows_; 
 int cols_; 
};

#endif // OPTBASEMATRIX_H

UPDATE: Here is a snippet from the debugger log:

Error   1   error C2143: syntax error : missing ';' before '<'  optbasematrix.h 17  TD2
Error   2   error C4430: missing type specifier - int assumed. Note: C++ does not support default-int   optbasematrix.h 17  TD2

I've tried modifying vector> data_; by vector > data_; and still get the same error :/ I read somewhere that my template class header (.h) and implementation (.cpp) must be in the same file... is this possibly related ?

UPDATE 2: Wow ! I had forgotten "using namespace std;". The problem seems fixed now !

Answer 1

Try:

vector<vector<T> > data_; 

Answer 2

You need to put a space between the two >.

 vector<vector<T> > data_;

Without the space, >> is treated as a stream-extraction/right-shift operator.

Additionally, you either need to declare operator+ as a free function or you must declare it with one parameter only:

// Member function
Matrix<T> operator+(const Matrix<T>& other) const;

// Free function (`friend` makes the function free
// even though it's declared within the scope of the class definition)
friend Matrix<T> operator+(const Matrix<T>& lhs, const Matrix<T>& rhs);