pointer to a pointer syntax differences between int *p and int **p C++

Question

Is there a difference of declaring int *p; or int **p; I know **p is used for a pointer to a pointer but *p can also be assigned to a pointer so my question is there a difference between them?

void main()
{

    int numDays;
    double sum = 0;
    double avg;
    cout << "Enter the number of days of sales";
    cin >> numDays;
    double *Sales = new double[numDays];
    double *p = Sales;
    for (int i = 0; i < numDays; i++)
    {
        cout << "enter how much you sold for day " << i << endl;
        cin >> *p;
        sum = sum + *p;
        p++;


    }


    avg = sum / (numDays);
    cout << "the sum is" << sum << endl;
    cout << "the avg is" << avg << endl;

    delete[]Sales;

why don't we use pointertopointers for a dynamic array such as this in this spot

double *Sales = new double[numDays];
        double *p = Sales;

or can you?

Yes. A regular `int *` points to a bunch of ints in memory. An `int **` points to a pointer to a bunch of ints in memory... — Millie Smith, Apr 18 '16 at 00:57
Possible duplicate of [Why use double pointer? or Why use pointers to pointers?](http://stackoverflow.com/questions/5580761/why-use-double-pointer-or-why-use-pointers-to-pointers) — jtbandes, Apr 18 '16 at 00:57
@MillieSmith Actually an `int **` points to *some number* of pointers, where each points to some number of `ints`. — Daniel Jour, Apr 18 '16 at 00:59
@MillieSmith - an `int**` pointes to a bunch of (as in 1 or more) `int*`s in memory. Those `int*`s may or may not point to `int`s. For example, they may all be NULL, in which case they don't point anywhere. — Pete Becker, Apr 18 '16 at 01:02
@PeteBecker Actually, an `int **` may not point to an `int *` in memory. It may be NULL. — Millie Smith, Apr 18 '16 at 04:01
@MillieSmith - and `int*` may not point to an `int` in memory. It may be NULL. But that wasn't your point, nor mine. — Pete Becker, Apr 18 '16 at 12:23
@PeteBecker that was pretty much half of your comment, actually. My point is you're being pedantic. Time to delete these comments and move on. — Millie Smith, Apr 18 '16 at 15:45

score 0 · Answer 1 · answered Apr 18 '16 at 00:57

0

They are different types. One level of indirection above an int, vs two levels.

answered Apr 18 '16 at 00:57

StoryTeller - Unslander Monica

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score 0 · Answer 2 · answered Apr 18 '16 at 01:02

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I know **p is used for a pointer to a pointer

Correct.

but *p can also be assigned to a pointer

But not to a pointer to a pointer.

so my question is there a difference between them?

Yes.

answered Apr 18 '16 at 01:02

user207421

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score 0 · Answer 3 · answered Apr 18 '16 at 01:02

0

int * ptr

pointer->value

int ** ptr

pointer->pointer->value

answered Apr 18 '16 at 01:02

Stephen

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pointer to a pointer syntax differences between int *p and int **p C++

3 Answers3