Function CSTL_u16string_insert_substr_at

pub unsafe extern "C" fn CSTL_u16string_insert_substr_at(
    instance: CSTL_UTF16StringRef,
    off: usize,
    other: CSTL_UTF16StringCRef,
    other_off: usize,
    count: usize,
    alloc: *mut CSTL_Alloc,
) -> bool

Inserts the substring at offset other_off in other with the length given by count at offset off in instance.

If off is outside of the range [instance, instance + CSTL_u16string_size(instance)] or if other_off is outside of the range [other, other + CSTL_u16string_size(other)] or if the length of the resulting string is greater than CSTL_u16string_max_size() this function has no effect and returns false, otherwise it returns true.