CODEWITHSUNDEEP
c
Hooli
Hooli

Reputation: 731

What is the difference between (int*) arr[2] and int* arr[2]?

Does (int*) arr[2] have to with typecasting? If yes, where is it used?

This problem arose when I tried to compile the follwing code :

    int* arr[2];
    int arr1[] = { 1,2};
    int arr2[] = { 1,6};
    arr[0] = arr1;
    arr[1] = arr2;

by replacing 

int* arr[2] with (int*)arr[2]

Thanks.

Upvotes: 2

Views: 6763

Answers (2)

AnT stands with Russia
AnT stands with Russia

Reputation: 320797

The problem with replacing int *arr[2] with (int *) arr[2] in your context is that the latter no longer conforms to the C grammar for declarations. According to the structure of C grammar, in int *arr[2] the * is attached to arr, not to int. Forcing it towards int by using extra () violates the suffix of a declaration.

You are allowed to use () in C declarations as long as it doesn't violate the syntactic structure of a declaration imposed by C grammar. For example, you can do

int *(arr)[2]; // same as `int *arr[2]`

or

int *(arr[2]); // same as `int *arr[2]`

or

int (*arr)[2]; // different from `int *arr[2]`, but still valid

but not your (int *) arr[2] or (int) *arr[2]. The latter are not declarations.

Upvotes: 2

Alexandru Barbarosie
Alexandru Barbarosie

Reputation: 3002

First one makes arr as an array of pointers to int. So your arr is a variable. That is a declaration line.

The second one: assuming that arr is a an array (which was allready declared!), takes the value which is arr[2] and casts a pointer to int type on it.

Upvotes: 3

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