How do you perform a deep copy of a two-dimensional array?

You perform a deep copy of a two-dimensional array by creating a new array and copying each element from the original array individually.

In computer programming, a deep copy is a process in which the elements of an array are copied, and any modifications made to the new array do not affect the original array. This is different from a shallow copy, where the new array simply references the original array, and changes to one will affect the other.

To perform a deep copy of a two-dimensional array, you would first need to create a new array with the same dimensions as the original. Then, you would iterate through each element in the original array, copying it to the corresponding position in the new array. This can be done using nested for loops, with the outer loop iterating through the rows and the inner loop iterating through the columns.

Here is an example in Java:

```java
int[][] original = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
int[][] copy = new int[original.length][];

for (int i = 0; i < original.length; i++) {
copy[i] = new int[original[i].length];
for (int j = 0; j < original[i].length; j++) {
copy[i][j] = original[i][j];
}
}
```

In this example, the `new int[original.length][]` creates a new two-dimensional array with the same number of rows as the original. The `new int[original[i].length]` in the outer loop creates a new array for each row, with the same number of columns as the original. The inner loop then copies each element from the original array to the new array.

It's important to note that this method only works for two-dimensional arrays with primitive data types. If the array contains objects, you would need to create a new instance of each object and copy its fields, to ensure that changes to the objects in the new array do not affect the original array. This is because objects in Java are passed by reference, so simply copying the object would result in both arrays pointing to the same object.