Question

我在空闲时间学习C语言。我熟悉C＃，Java和Python。作为练习，我在C中写了一个链表。它运行正常，有错误处理等等。

但是，我正在尝试修复内存泄漏。我知道C没有自动垃圾收集。那么在我删除列表后，如何“释放”列表中的某个成员呢？我写了一个名为removeAllList（）的函数。该函数成功从列表中删除该成员，但我知道仍然分配了该成员的内存。我尝试使用free（[myArgument]）函数，但它会产生无限循环。你能说明我将使用free（）函数在我的代码中成功释放已删除成员的内存吗？

#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: %i\nContents: ", list->size);
        while(current->next != NULL){
            printf("%i, ", current->data);
            current = current->next;
        }
        printf("%i\n", 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

你不应该消耗内存NULL。您需要free()这样的人free(mynode->next);，但只有在您确定之前有malloc()来电时才需要free(list->root);。

在您的代码中，您需要使用list->root = NULL;代替free(prev->next);和prev->next = NULL;代替{{1}}

删除链接列表后释放内存

1 个答案: