variably modified ‘_memory’ at file scope

At file scope, the C language does not allow the declaration of a variably modified identifier named '_memory'. This means that you cannot declare a variable with the name '_memory' at the top-level of a C file if it has a variable-length array type. Variable-length arrays are arrays whose size is determined at runtime, rather than at compile-time.

The C language requires that the size of an array be known at compile-time, which allows the compiler to allocate the necessary memory for the array. However, with variable-length arrays, the size is not known until runtime, which makes it difficult for the compiler to allocate the memory.

If you need to declare a variable with a variable-length array type at file scope, you can use a pointer to dynamically allocate the memory at runtime. This allows you to allocate the necessary memory when the program is running, rather than at compile-time.

Here's an example of how you can declare a pointer to a variable-length array at file scope:

#include <stdlib.h>

int main() {
    // Declare a pointer to a variable-length array
    int (*ptr)[10];

    // Dynamically allocate memory for the array
    ptr = malloc(sizeof(int[10]));

    // Use the array
    (*ptr)[0] = 10;

    // Free the allocated memory
    free(ptr);

    return 0;
}

In this example, the pointer 'ptr' is declared at file scope, and it points to a variable-length array of integers. The memory for the array is dynamically allocated using the 'malloc' function, and the 'free' function is used to free the allocated memory when it is no longer needed.

Note that using variable-length arrays can have implications for performance and memory usage, so it's important to consider whether they are necessary for your specific use case.