C++ Pointer to const array of const pointers

Question

I've created a const array of const pointers like so:

const char* const sessionList[] = {
    dataTable0,
    dataTable1,
    dataTable2,
    dataTable3
};

What is the correct syntax for a regular non-const pointer to this array? I thought it would be const char**, but the compiler thinks otherwise.

Technically, your const char * * would be equivalent to your array, since this is what your array will decay to when passed to a function. You'd need an extra indirection to get a pointer to the array. Or something like const char * [] *, but I'm not sure if that one is valid — KABoissonneault
– KABoissonneault, Commented Jun 23, 2016 at 18:06
It looks like the type of &sessionList is const char * const (*)[4], but I'm struggling to declare a variable with such a type. — KABoissonneault
– KABoissonneault, Commented Jun 23, 2016 at 18:09
You shoud clarify whether you want a pointer to an array or a pointer to an element of an array. Those two are different things. — juanchopanza
– juanchopanza, Commented Jun 23, 2016 at 18:12
@KABoissonneault: The array decays to const char * const * when you use it in most contexts (everything except sizeof, decltype and &) — Chris Dodd
– Chris Dodd, Commented Jun 23, 2016 at 18:12

juanchopanza · Accepted Answer · 2016-06-23 18:10:54Z

6

If you actually need a pointer to an array, as your title suggests, then this is the syntax:

const char* const (*ptr)[4] = &sessionList;

answered Jun 23, 2016 at 18:10

juanchopanza

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R Sahu · Accepted Answer · 2016-06-23 18:13:05Z

5

const char* const sessionList[] = { ... };

is better written as:

char const* const sessionList[] = { ... };

Type of sessionList[0] is char const* const.
Hence, type of &sessionList[0] is char const* const*.

You can use:

char const* const* ptr = &sessionList[0];

or

char const* const* ptr = sessionList;

That declares a pointer to the elements of sessionList. If you want to declare a pointer to the entire array, it needs to be:

char const* const (*ptr)[4] = &sessionList;

answered Jun 23, 2016 at 18:13

R Sahu

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Chris Dodd · Accepted Answer · 2016-06-23 18:02:50Z

2

The same type as you declared for the array elements, with an extra * added:

const char* const *

answered Jun 23, 2016 at 18:02

Chris Dodd

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1 Comment

Chris Dodd Over a year ago

@juanchopanza: That's a pointer type that can point at any element of the array, which is usually what people mean by the term 'pointer to the array' -- the pointer type that the array name turns into when you use it.

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