检查const数组是否在编译期间排序（C语言）

Question

In C language, how to check during compile time if a const array is sorted (in ascending order) or not.

Given an array like this: const int a[] = {4,5,6,8};

Compilation should fail with error if the above array is not sorted.

Is that even possible?

Answer 1

This is very difficult to do generically at compilation time, it may even be impossible with the standard tools (preprocessor, etc).

Perhaps a better solution would be to, as soon as possible after array creation, simply have code check it (which you can also disable like assert ):

const int a[] = { 4, 5, 6, 8 };
#ifndef NDEBUG
for (int i = 1; i < sizeof(a) / sizeof(a[0]); i++) {
    if (a[i-1] > a[i]) {
        fprintf (stderr, "%s(%d) Check your arrays\n", __FILE__, __LINE__);
        exit(1);
    }
}
#endif