Re: [Dev-C++] Basic Case in recursivity

[Per W. <pw...@ia...>]

See below:

/Per W

On Sun, 8 Jun 2003, Andr=E9 Mac=E1rio Barros wrote:

> Dear Users,
>   Please consider the followin code:
>
> #include <iostream>
> using std::cout;
> using std::endl;
> #include <cstdlib>
>
> void someFunction(int [], int);
>
> int main()
> {
>    const int arraySize =3D 10;
>    int a[arraySize] =3D {32, 27, 64, 18, 95, 14, 90, 70, 60, 37};
>
>    cout << "Array values are:" << endl;
>    someFunction(a, arraySize);  // the array is printed in reversal order
>    cout << endl;
>
>    system("PAUSE");
>    return 0;
> }
>
> 1-void someFunction(int b[], int size)
> 2-{
> 3-   if(size > 0)
> 4-   {
> 5-      someFunction(&b[1], size-1);
> 6-      cout << b[0] << " ";
> 7-   }
> 8-}

PWM: This one would (try to) emit:
cout << a[1] << " "; (call stack now have 10 levels of someFunction)
cout << a[2] << " ";
=2E..
cout << a[10] << " "; (now only one level of someFunction on the stack)

PWM: As you can see, you have an off-by-one error in the code.

PWM: Since this is a linear problem, it is inefficient to use a recursive
solution. Just use a for loop instead. Had it been a tree you wanted to
dump, then recursion would have been suitable.

>
> A) I allways worked with recursive functions that had an explict
>    Basic Case, i.e., an "if" statement, and a return command;
> B) Here in this recursive function there isn=B4t a if/return command
>    as you can see. I think when the calls arrive in the
>    "someFunction(&b[9], size-9);", the cout in line 6 is executed;
>
> My Questions:
> 1) Is there any implicit basic case for recursive functions without an
>    explicit if/return command?
> 2) How is the dynamic of this function? All the calls to someFunction are
>    made and only after this the command of line 6 is made? In the last ca=
ll
>    for the 10th element?
>
> Regards
> Andre
>
>
>
>
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