On Monday, 25 June 2018 at 17:45:01 UTC, zbr wrote:
Hi, this question is not specifically D related but I'll just
ask anyway. Consider the following snippet:
void mergeSort(int[] arr, int l, int r)
{
if (l < r) // 1
{
int m = l+(r-l)/2; // 2
mergeSort(arr, l, m); // 3
mergeSort(arr, m+1, r); // 4
merge(arr, l, m, r); // 5
} // 6
} // 7
mergeSort(arr, 0, 4);
When I see this, I visualize the recursion to perform this way:
mergeSort(arr, 0, 4):
0 < 4 ? true: mergeSort(0, 2):
0 < 2 ? true: mergeSort(0, 1):
0 < 1 ? true: mergeSort(0, 0):
0 < 0 ? false: //reach the end of mergeSort /
reach line 6 and then 7
I don't see the computer ever reaching line 4 and 5? Obviously
I'm wrong but where is my mistake?
Thanks.
It's a stack (https://en.wikipedia.org/wiki/Call_stack).
When the program calls a function it is pushed onto the stack. If
that function returns it pops from the stack and the previous
function gets to continue execution from where it stopped before.
