c-删除链表后释放内存

Question

我在空闲时间学习C。我熟悉C#、Java和Python。作为练习，我在C中写了一个链表。它功能正确，有错误处理等。

然而，我正在努力修复内存泄漏。我知道C没有自动垃圾收集功能。那么，在删除列表后，我如何"释放"列表中的成员呢？我编写了一个名为removeAllList（）的函数。该函数成功地从列表中删除了该成员，但我知道该成员的内存仍在分配中。我尝试过使用free（[myArgument]）函数，但它会导致无限循环。你能告诉我在哪里使用free（）函数来成功地为代码中被删除的成员释放内存吗？

#include<stdio.h>
#include<stdlib.h>
struct Member{
    int data;
    struct Member *next;
};
struct List{
    int size;
    struct Member *root;
};
struct Member *createMember(int i){
    struct Member *new;
    new = malloc(sizeof(struct Member));
    new->data = i;
    new->next = NULL;
    return new;
}
struct List *createList(int i){
    struct List *new;
    new = malloc(sizeof(struct List));
    new->root = createMember(i);
    new->size = 1;
    return new;
}
void printList(struct List *list){
    struct Member *current = list->root;
    //error handling for empty list
    if(list->size < 1){
        printf("Error: List is empty");
    }
    //if list is not empty
    else{
        printf("List size: %inContents: ", list->size);
        while(current->next != NULL){
            printf("%i, ", current->data);
            current = current->next;
        }
        printf("%in", current->data);
    }
}
void addList(struct List *list, int i){
    struct Member *current = list->root;
    while(current->next != NULL){
        current = current->next;
    }
    current->next = createMember(i);
    list->size++;
}
void removeAllList(struct List *list, int i){
    struct Member *current = list->root;
    struct Member *prev = list->root;
    if(list->size < 1){
        //list is empty, end function now
        return;
    }
    //remove all matching list head
    while(current->data == i){
        if(list->size <= 1){
            list->root = NULL;
            list->size--;
            //list is empty, end function now
            return;
        }
        else{
            list->root = current->next;
            current = list->root;
            list->size--;
        }
    }
    current = current->next;
    //remove all matching list body
    while(current->next != NULL && list->size > 1){
        if(current->data == i){
            prev->next = current->next;
            list->size--;
        }
        prev = current;
        current = current->next;
    }
    //remove all matching list tail
        if(current->data == i && list->size > 1){
            prev->next = NULL;
            list->size--;
        }
}
main(){
        struct List *myList; 
        myList = createList(4);
        addList(myList, 12);
    addList(myList, 9);
    addList(myList, 4);
    addList(myList, 43);
    addList(myList, 4);
        printList(myList);
    removeAllList(myList, 4);
    printList(myList);
}

Answer 1

您不应该制作消耗内存的东西NULL。你需要像这样free()：free(mynode->next);，但前提是你确定之前有malloc()调用。

在您的代码中，您需要使用free(list->root);而不是list->root = NULL;，使用free(prev->next);而不是prev->next = NULL;