. Một nguyên tắc ghi nhớ tốt để thông qua các thông số bằng con trỏ là: Khi bạn chọn tên cho một tham số, bạn phải bắt đầu tên này với cácHình ảnh cũng cho thấy rằng khi các mã khách hàng cần các giá trị của lĩnh vực xi lanh (ví dụ, để tính toán khối lượng xi lanh, mở rộng quy mô, in ấn, hoặc thiết lập các giá trị trường), | file Administrator General 20English 20Learning it2002-7-6 include cstring using SimpcsPDFMergeand Split Unregistered Version - http union StreetOrPOB char street 30 alternative interpretations long int POB struct Address char first 30 int kind 0 street address 1 . StreetOrPOB second either one or another meaning char third 30 int main Address a1 a2 strcpy Doe John address with street strcpy 15 Oak Street 0 strcpy Anytown MA 02445 strcpy King Amy 761 1 address with POB strcpy Anytown MA 02445 cout endl if 0 check data interpretation cout endl else cout . endl cout endl cout endl cout endl if 0 check data interpretation cout endl else cout . endl cout endl return 0 This is nice but it introduces yet another level into the hierarchical structure of types. As a result the programmer has to use names like and this is no fun. Meanwhile the only use of type StreetOrPOB in the program is with type Address. To remedy this C supports anonymous unions. They have no name and no variable of this type can be defined however their fields can be used without any qualification. For example we can define type Address without using type StreetOrPOB but using an anonymous union instead. struct Address file Administrator General 20English 20Leaming it2002-7-6 241 of 1187 8 17 2002 2 57 49 PM file Administrator General 20English 20Learning it2002-7-6 char first 30 int kSimpo PDF Merge and Split Unregistered Version -Ihttp . union char street 30 long int POB no second field of type StreetOrPOB char third 30 The union type is gone but type Address now has two alternative fields street and POB and they can be referred to by name as in any other field. Of course it remains the responsibility of the .
