zero length arrays [duplicate]

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The use is for dynamic-length arrays. You can allocate the memory using malloc(), and have the array reside at the end of the structure:

struct arr *my_arr = malloc(sizeof *my_arr + 17 * sizeof *my_arr->list);
my_arr->cnt = 17;
my_arr->list[0].size = 0;
my_arr->list[1].name = "foo";

Actually being able to use 0 for the length is (as pointed out in a comment) a GCC extension. In C99, you can leave out the size literal altogether for the same effect.

Before these things were implemented, you often saw this done with a length of 1, but that complicates the allocation a bit since you must compensate when computing the memory needed.

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