C++ 源文件无法自动链接

Question

C++ VS，在头文件中给出了函数声明，在另一个源文件里给出定义，main（）所在源文件和上述两个文件都已包含在同一项目里，但编译时对在另一源文件中定义的函数会报错“无法解析的外部命令”，而在main函数所在源文件中include包含函数定义的源文件，则编译通过。不应该是自动链接吗？

//Matrix.h

#ifndef A
#define A
#include<iostream>
#include<vector>
using namespace std;
template<typename elemtype>
class Matrix {
public:
    Matrix(elemtype seq[16])
    {
        vector<elemtype> a(4);
        for (int ix = 0; ix < 4; ix++)
        {
            _elems.push_back(a);
        }
        int row,column;
        for (int ix = 0; ix < 16; ix++)
        {
            row = ix / 4,column=ix%4;
            _elems[row][column] = seq[ix];
        }
    }
    Matrix()
    {
        vector<elemtype> a(4);
        for (int ix = 0; ix < 4; ix++)
        {
            _elems.push_back(a);
        }
    }
    elemtype& operator()(int row, int column)
    {
        return _elems[row][column];
    }
    elemtype operator()(int row, int column)const
    {
        return _elems[row][column];
    }
    Matrix operator+(const Matrix&)const;//
    Matrix operator*(const Matrix&)const;
    void print(ostream& os = cout)const;
    Matrix& operator+=(const Matrix&);
private:
    vector<vector<elemtype> > _elems;

};
#endif


//Matrix.cpp
#include"Matrix.h"
template<typename elemtype>
Matrix<elemtype> Matrix<elemtype>::operator*(const Matrix& rhs)const
{
    Matrix new_Matrix;
    int row, column;
    for (int ix = 0; ix < 16; ix++)
    {
        row = ix / 4, column = ix % 4;
        float sum = 0;
        for (int ix = 0; ix < 4; ix++)
        {
            sum += this->_elems[row][ix] * rhs._elems[ix][column];
        }
        new_Matrix._elems[row][column]=sum;
    }
    return new_Matrix;
}
template<typename elemtype>
Matrix<elemtype> Matrix<elemtype>::operator+(const Matrix& rhs)const
{
    Matrix new_Matrix;
    int row, column;
    for (int ix = 0; ix < 16; ix++)
    {
        row = ix / 4;
        column = ix % 4;
        new_Matrix._elems[row][column] =
            this->_elems[row][column] + rhs._elems[row][column];
    }
    return new_Matrix;
}
template<typename elemtype>
Matrix<elemtype>& Matrix<elemtype>::operator+=(const Matrix& rhs)
{
    *this = *this + rhs;
    return *this;
}
template<typename elemtype>
void Matrix<elemtype>::print(ostream& os)const
{
    int row, column;
    for (int ix = 0; ix < 16; ix++)
    {
        row = ix / 4, column = ix % 4;
        os << _elems[row][column] << "   ";
        if (column == 3)
            os << '\n';
    }
}

//Matrix_test.cpp
#include"Matrix.h"
using namespace std;
int main()//调用了在Matrix.cpp中定义的函数
{
...
}

报错无法解析的外部命令

若在主函数所在源文件中include“Matrix.cpp"则编译通过。

Answer 1

模板的声明定义都放到头文件，参考这篇博文(https://blog.csdn.net/imred/article/details/80261632?spm=1001.2101.3001.6650.1&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7Edefault-1-80261632-blog-108782175.pc_relevant_multi_platform_whitelistv1_exp2&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7Edefault-1-80261632-blog-108782175.pc_relevant_multi_platform_whitelistv1_exp2&utm_relevant_index=2)
如有帮助，请采纳，谢谢