CODEWITHSUNDEEP
c
David542
David542

Reputation: 110592

Compound literals with pointers

To pass a 2d array to a function with the array inline, I can do the following:

void print_arr2(int (*arr)[3], size_t size);

print_arr2((int[2][3]) {{1,2,3}, {3,6,9}}, 2);
print_arr2((int[][3]) {{1,2,3}, {3,6,9}}, 2);

However, the following notation doesn't seem to be supported or I am entering it in incorrectly:

print_arr2((int(*)[3]) {{1,2,3}, {3,6,9}}, 2); // pointer to int [3]

Is this last format not supported, or what's the reason that that fails in trying to use a compound literal for it?

Upvotes: 2

Views: 233

Answers (1)

Eric Postpischil
Eric Postpischil

Reputation: 224596

(int(*)[3]) {{1,2,3}, {3,6,9}} creates a compound literal that is a pointer to an array of three int and then attempts to initialize it with two lists of three int. A pointer must be initialized with an address.

A solution is to create a 2×3 array, which will be automatically converted to a pointer to its first element, yielding a pointer to an array of three int: (int [2][3]) {{1, 2, 3}, {3, 6, 9}}.

Upvotes: 1

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