Use return value of function as array size initialiser in C

Question

I've written a function in C to get the size of the terminal:

int get_terminal_size()

{

    struct winsize w;

    ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);



    return w.ws_row * w.ws_col;

}

However, I want to use it as the size parameter when initialising an array in a struct:

struct level

{

    [...]

    char level_data[get_terminal_size()];

}

However, this doesn't compile, as the compiler tells me that the initialiser element needs to be constant (which makes sense, but assigning the return value to a

const int

doesn't work either).

Is there any other way of doing what I need to do in C?

Thanks in advance.

Answer 1

The size of the array has to be known at compilation time. If you want to allocate memory dynamically you have to use malloc.

char *level_data = malloc(get_terminal_size());
if (level_data == NULL)
{ /* handle allocation failure */ }
/* ...Do something with your array... */
free(level_data);

People in comments, thank you for the corrections.

Use return value of function as array size initialiser in C

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