C++定义一个m行n列的矩阵类

class matrix { public: matrix():r(0), p(0), j(NULL) {} matrix(int m,int n):r(m),p(n) { j = new int*[m]; for(int i = 0; i < m; i++) { j[i] = new int[n]; } } ~matrix() { for(int i = 0; i < r; i++) {