[英]pointer to function that return pointer to struct
我正在嘗試編寫一種定義如下的ArrayList
(結構):
typedef struct {
int reservedSize; // reserved size
int size; // Size of list
void ** pElements; //pointer to list elements
void (*deleteArrayList)();
void (*add)();
void (*remove)();
void (*set)();
void* (*get)();
int (*indexOf)();
int (*len)();
void (*clear)();
void (*push)();
void* (*pop)();
int (*contains)();
int (*isEmpty)();
//Extras
int (* containsAll)();
struct ArrayList* (*clone)(); //trouble1
struct ArrayList* (*subList)();//trouble2
} ArrayList;
如您所見,兩個元素分別輸入int
和指向函數的指針,但是我對后兩個元素只有麻煩。 我有一個初始化器,如下所示:
ArrayList* al_newArrayList(void) {
ArrayList* list;
list = (ArrayList *) malloc (sizeof(ArrayList));
list->size = 0;
list->pElements = malloc(sizeof(void *) * 10);
list->reservedSize = 10;
list->add = al_add;
list->deleteArrayList = al_deleteArrayList;
list->remove = al_remove;
list->set = al_set;
list->get = al_get;
list->indexOf = al_indexOf;
list->len = al_len;
list->clear = al_clear;
list->push = al_push;
list->pop = al_pop;
list->contains = al_contains;
list->isEmpty = al_isEmpty;
list->containsAll = al_containsAll;
list->clone = al_clone;//trouble1
list->subList = al_subList;//trouble2
return list;
}
該程序可以運行,但是會出現運行時錯誤,並且在以下位置有關於錯誤引用的警告:
list->clone = al_clone;//trouble1
list->subList = al_subList;//trouble2
即使這些功能都可以,但是程序已關閉。 你有什么主意嗎? 語法錯誤?
typedef struct {
int reservedSize; // reserved size
int size; // Size of list
// ...
struct ArrayList* (*clone)(); //trouble1
struct ArrayList* (*subList)();//trouble2
} ArrayList;
到編譯器到達“麻煩”行時,還沒有名為struct ArrayList
類型。
存在沒有定義標記名的結構類型。
在該定義的末尾,將定義一個名為ArrayList
的類型(沒有標記名的結構類型)。
解:
定義類型struct ArrayList
typedef struct ArrayList { // define type with tagname
int reservedSize; // reserved size
int size; // Size of list
// ...
struct ArrayList* (*clone)(); //trouble1
struct ArrayList* (*subList)();//trouble2
} ArrayList;
感謝@pmg指出我。
typedef struct ArrayList ArrayList;
struct ArrayList{
int reservedSize; // reserved size
int size; // Size of list
void ** pElements; //pointer to list elements
void (*deleteArrayList)();
void (*add)();
void (*remove)();
void (*set)();
void* (*get)();
int (*indexOf)();
int (*len)();
void (*clear)();
void (*push)();
void* (*pop)();
int (*contains)();
int (*isEmpty)();
//Extras
int (* containsAll)();
struct ArrayList* (*clone)(); //trouble1
struct ArrayList* (*subList)();//trouble2
};
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