CODEWITHSUNDEEP
c++classtemplates
Charles Ray
Charles Ray

Reputation: 480

Error: expected constructor, destructor, or type conversion before ‘::’ token

I am getting an error when trying to compile my class.

The error:

Matrix.cpp:13: error: expected constructor, destructor, or type conversion before ‘::’ token

Matrix.h

#ifndef _MATRIX_H
#define _MATRIX_H

template <typename T>
class Matrix {
public:
    Matrix();
    ~Matrix();
    void set_dim(int, int);     // Set dimensions of matrix and initializes array
    unsigned int get_rows();    // Get number of rows
    unsigned int get_cols();    // Get number of columns
    void set_row(T*, int);      // Set a specific row with array of type T
    void set_elem(T*, int, int);// Set a specific index in the matrix with value T
    bool is_square();           // Test to see if matrix is square
    Matrix::Matrix add(Matrix); // Add one matrix to another and return new matrix
    Matrix::Matrix mult(Matrix);// Multiply two matrices and return new matrix
    Matrix::Matrix scalar(int); // Multiply entire matrix by number and return new matrix

private:
    unsigned int _rows;         // Number of rows
    unsigned int _cols;         // Number of columns
    T** _matrix;                // Actual matrix data

};

#endif  /* _MATRIX_H */

Matrix.cpp

#include "Matrix.h"
template <typename T>
Matrix<T>::Matrix() {
}

Matrix::~Matrix() { // Line 13
}

main.cpp

#include <stdlib.h>
#include <cstring>
#include "Matrix.h"

int main(int argc, char** argv) {
    Matrix<int> m = new Matrix<int>();
    return (EXIT_SUCCESS);
}

Upvotes: 0

Views: 2123

Answers (2)

Oleg Svechkarenko
Oleg Svechkarenko

Reputation: 2516

Define destructor as 

template <typename T>
Matrix<T>::~Matrix() {
}

And other error is that you cannot place implementation of class template in .cpp-file Template Factory Pattern in C++

Upvotes: 3

James McNellis
James McNellis

Reputation: 355069

Matrix::~Matrix() { }

Matrix is a class template. You got the constructor definition right; the destructor (and any other member function definitions) need to match.

template <typename T>
Matrix<T>::~Matrix() { }

Matrix<int> m = new Matrix<int>();

This won't work. new Matrix<int>() yields a Matrix<int>*, with which you cannot initialize a Matrix<int>. You don't need any initializer here, the following will declare a local variable and call the default constructor:

Matrix<int> m;

Upvotes: 6

Related Questions