C pointer to array/array of pointers disambiguation

int* arr[8]; // An array of int pointers.
int (*arr)[8]; // A pointer to an array of integers

The third one is same as the first.

The general rule is operator precedence. It can get even much more complex as function pointers come into the picture.

Use the cdecl program, as suggested by K&R.

$ cdecl
Type `help' or `?' for help
cdecl> explain int* arr1[8];
declare arr1 as array 8 of pointer to int
cdecl> explain int (*arr2)[8]
declare arr2 as pointer to array 8 of int
cdecl> explain int *(arr3[8])
declare arr3 as array 8 of pointer to int
cdecl>

It works the other way too.

cdecl> declare x as pointer to function(void) returning pointer to float
float *(*x)(void )

I don't know if it has an official name, but I call it the Right-Left Thingy(TM).

Start at the variable, then go right, and left, and right...and so on.

int* arr1[8];

arr1 is an array of 8 pointers to integers.

int (*arr2)[8];

arr2 is a pointer (the parenthesis block the right-left) to an array of 8 integers.

int *(arr3[8]);

arr3 is an array of 8 pointers to integers.

This should help you out with complex declarations.

Here's an interesting website that explains how to read complex types in C: http://www.unixwiz.net/techtips/reading-cdecl.html

I guess the second declaration is confusing to many. Here's an easy way to understand it.

Lets have an array of integers, i.e. int B[8].

Let's also have a variable A which points to B. Now, value at A is B, i.e. (*A) == B. Hence A points to an array of integers. In your question, arr is similar to A.

Similarly, in int* (*C) [8], C is a pointer to an array of pointers to integer.

int *arr1[5]

In this declaration, arr1 is an array of 5 pointers to integers. Reason: Square brackets have higher precedence over * (dereferncing operator). And in this type, number of rows are fixed (5 here), but number of columns is variable.

int (*arr2)[5]

In this declaration, arr2 is a pointer to an integer array of 5 elements. Reason: Here, () brackets have higher precedence than []. And in this type, number of rows is variable, but the number of columns is fixed (5 here).