cpointersvariable-length-arrayanonymous-objects

How to assign anonymous VLA to pointer?

Currently I am assigning a VLA to a pointer as follows

struct Foo {
    int* array;
};

int array[size];

struct Foo foo = {
    .array = array;
};

Is it possible to replace this with an "anonymous" array?

What I tried:

struct Foo foo = {
    .array = (int[size]) {} // fatal error: variable-sized object may not be initialized
};

What I was hoping for:

struct Foo foo = {
    .array = int[size]; // something similar to this if I am making any sense.
};

PS: I am not looking for dynamic memory allocation (malloc/calloc).

Solution

  • Is it possible to replace this with an "anonymous" array?

    No.

    Specifically, you are asking how to create an anonymous variable-length array. C does not support those.

    Of compound literals ((){}), the C standard says:

    C17 §6.5.2.5 ¶1 The type name shall specify a complete object type or an array of unknown size, but not a variable length array type.

    Your only options are the nonstandard alloca/_alloca.