如何释放仅包含指针的结构

Question

我有一个结构,你看到如下:

typedef struct _List {
    Person *person; // pointer for people list
    DoList *do; // Kinda timer, for checking list in some intervals
} List;

有没有必要释放这个结构？如果是这样,我怎么能释放它？

Answer 1

如果动态分配结构,则必须释放结构.如果动态分配成员并且在其他任何地方没有对它们的引用,则必须在释放结构之前释放其成员.

这里有些例子:

void freeNotRequiredHere() {
    List            nonDynamicList;
    Person          nonDynamicPerson;
    DoList          nonDynamicDoList;

    nonDynamicList.person = &nonDynamicPerson;
    nonDynamicList.do = &nonDynamicDoList;
}


void freeRequiredForStructListOnly() {
    List            *dynamicList;
    Person          nonDynamicPerson;
    DoList          nonDynamicDoList;

    dynamicList = (List *) malloc( sizeof(struct List) );

    dynamicList->person = &nonDynamicPerson;
    dynamicList->do = &nonDynamicDoList;

    free( dynamicList );
}


void freeRequiredForStructListAndPersonOnly() {
    List            *dynamicList;
    Person          *dynamicPerson;
    DoList          nonDynamicDoList;

    dynamicList = (List *) malloc( sizeof(struct List) );
    dynamicPerson = (Person *) malloc( sizeof(Person) );

    dynamicList->person = dynamicPerson;
    dynamicList->do = &nonDynamicDoList;

    free( dynamicPerson );
    free( dynamicList );
}


void freeRequiredForStructListAndPersonOnly( DoList *notSureDoList ) {
    List            *dynamicList;
    Person          *dynamicPerson;

    dynamicList = (List *) malloc( sizeof(struct List) );
    dynamicPerson = (Person *) malloc( sizeof(Person) );

    dynamicList->person = dynamicPerson;
    dynamicList->do = notSureDoList;

    // maybe notSureDoList was allocated with malloc(),
    // maybe it is a non-dynamic stack variable.
    // the calling function should deal with free()'ing notSureDoList

    free( dynamicPerson );
    free( dynamicList );
}

Answer 2

void free_mystruct(struct_List *a_ptr){
  free(a_ptr->person);
  free(a_ptr->do);
  free(a_ptr);
}

如果您使用malloc最初分配内存。