Declare a C/C++ function returning pointer to array of integer pointers

Declare “a function with argument of int* which returns pointer to an array of 4 integer pointers”.

At the first glance it may look complex, we can declare the required function with a series of decomposed statements.

1. We need, a function with argument int *,

function(int *)

2. a function with argument int *, returning pointer to

(*function(int *))

3. a function with argument int *, returning pointer to array of 4



(*function(int *))[4]

4. a function with argument int *, returning pointer to array of 4 integer pointers

int *(*function(int *))[4];

How can we ensure that the above declaration is correct? The following program can cross checks our declaration,

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#include<stdio.h>
  
// Symbolic size
#define SIZE_OF_ARRAY (4)
  
// pointer to array of (SIZE_OF_ARRAY) integers
typedef int *(*p_array_t)[SIZE_OF_ARRAY];
  
// Declaration : compiler should throw error
// if not matched with definition
int *(*function(int *arg))[4];
  
// Definition  : 'function' returning pointer to an
// array of integer pointers
p_array_t function(int *arg)
{
   // array of integer pointers
   static int *arr[SIZE_OF_ARRAY] = {NULL};
  
   // return this
   p_array_t pRet = &arr;
  
   return pRet;
}
  
int main()
{          
}

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The macro SIZE_OF_ARRAY is used for symbolic representation of array size. p_array_t is typedefined as “pointer to an array of 4 integers”. If our declaration is wrong, the program throws an error at the ‘function‘ definition.

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