Idiom #309 Clone a 2D array

Create the new 2-dimensional array y containing a copy of the elements of the 2-dimensional array x.

x and y must not share memory. Subsequent modifications of y must not affect x.

integer, allocatable, dimension(:,:) :: y

y = x

buf := make([]T, m*n)
y = make([][]T, m)
for i := range y {
	y[i] = buf[:n:n]
	buf = buf[n:]
	copy(y[i], x[i])
}

Demo

func clone2D[M ~[][]T, T any](in M) (out M) {
	if len(in) == 0 {
		return nil
	}

	m, n := len(in), len(in[0])

	buf := make([]T, m*n)

	out = make(M, m)
	for i := range out {
		out[i] = buf[:n:n]
		buf = buf[n:]
		copy(out[i], in[i])
	}
	return out
}

Demo

int[][] y = new int[x.length][];
for(int index1 = 0; index1 < x.length; index1++) {
	y[index1] = new int[x[index1].length];
	for(int index2 = 0; index2 < x[index1].length; index2++) {
		y[index1][index2] = x[index1][index2];
	}
}