Using std::copy to deep copy 2D array in C++ got Segmentation fault

Question

I want to use the following method to deep copy two-dimensional array a to two-dimensional array b, but when running to std::copy, Segmentation fault is reported.

int a_l = 1000;
int b_l = 513;

double ** a;
double ** b;

// Allocate memory
a = new double *[a_l];
for (int i = 0; i < a_l; ++i) {
    a[i] = new double[b_l];
}

// Get data for array a
GetData(a);

// Copy a -> b

b = new double *[a_l];
for (int i = 0; i < a_l; ++i) {
    b[i] = new double[b_l];
}

std::copy(&a[0][0], &a[0][0] + a_l * b_l, &b[0][0]);

Answer 1

Just use std::array or std::vector and you can simply use a = b; to copy.