Array to pointer decay and passing multidimensional arrays to functions

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You got it slightly wrong: moreThings also decays to a pointer to the first element, but since it is an array of an array of chars, the first element is an “array of 8 chars”. So the decayed pointer is of this type:

char (*p)[8] = moreThings;

The value of the pointer is of course the same as the value of &moreThings[0][0], i.e. of the first element of the first element, and also the same of &a, but the type is a different one in each case.

Here’s an example if char a[N][3]:

+===========================+===========================+====
|+--------+--------+-------+|+--------+--------+-------+|
|| a[0,0] | a[0,1] | a[0,2]||| a[1,0] | a[1,1] | a[1,2]|| ...
|+--------+--------+-------+++--------+--------+-------++ ...
|            a[0]           |            a[1]           |
+===========================+===========================+====
                                    a
^^^
||+-- &a[0,0]
|+-----&a[0]
+-------&a

  • &a: address of the entire array of arrays of chars, which is a char[N][3]

  • &a[0], same as a: address of the first element, which is itself a char[3]

  • &a[0][0]: address of the first element of the first element, which is a char

This demonstrates that different objects may have the same address, but if two objects have the same address and the same type, then they are the same object.

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