c++ - 我处理这个的方式有内存问题吗？

Question

我正在为 Eigen QR 编写一个包装器供我个人使用，我想知道我的实现中是否存在任何内存泄漏或未记录的行为，尤其是在函数 void get_QR(double* A, int m, int n , double*& Q, double*& R).答案如预期。这与我之前的问题有关 here .

using std::cout;
using std::endl;
using namespace Eigen;

/*!
 Obtains the QR decomposition as A=QR, where all the matrices are in Eigen MatrixXd format.
 */
void get_QR(MatrixXd A, MatrixXd& Q, MatrixXd& R) {

        int m           =       A.rows();
        int n           =       A.cols();
        int minmn       =       min(m,n);

        //      A_E     =       Q_E*R_E.
        HouseholderQR<MatrixXd> qr(A);
        Q  =   qr.householderQ()*(MatrixXd::Identity(m, minmn));
        R  =   qr.matrixQR().block(0, 0, minmn, n).triangularView<Upper>();
}

/*!
 Obtains the QR decomposition as A=QR, where all the matrices are in double format.
 */
void get_QR(double* A, int m, int n, double*& Q, double*& R) {
        MatrixXd Q_E, R_E;
        int minmn       =       min(m,n);

        //      Maps the double to MatrixXd.
        Map<MatrixXd> A_E(A, m, n);

        get_QR(A_E, Q_E, R_E);

        Q       =       (double*)realloc(Q_E.data(), m*minmn*sizeof(double));
        R       =       (double*)realloc(R_E.data(), minmn*n*sizeof(double));
}


int main(int argc, char* argv[]) {
        srand(time(NULL));

        int m   =       atoi(argv[1]);
        int n   =       atoi(argv[2]);

//      Check the double version.
        int minmn       =       min(m,n);
        double* A       =       (double*)malloc(m*n*sizeof(double));
        double* Q       =       (double*)malloc(m*minmn*sizeof(double));
        double* R       =       (double*)malloc(minmn*n*sizeof(double));

        double RANDMAX  =       double(RAND_MAX);
        //      Initialize A as a random matrix.
        for (int index=0; index<m*n; ++index) {
                A[index]        =       rand()/RANDMAX;
        }

        get_QR(A, m, n, Q, R);
        std::cout << Q[0] << std::endl;

//      Check the MatrixXd version.
        Map<MatrixXd> A_E(A, m, n);
        MatrixXd Q_E, R_E;
        get_QR(A_E, Q_E, R_E);

        cout << Q[0] << endl;
        cout << Q_E(0,0) << endl;

        free(A);
        free(Q);
        free(R);
}

例如，我得到输出为

-0.360995
-0.360995
-0.360995

Answer 1

realloc不保证与 operator new[] 兼容和 operator delete[] , 只有 malloc和 free .

我会替换掉你所有的 double*指针 std::vector<double>对象。