引发了未经处理的异常:读取访问权限冲突

问题描述：

请大神指教一下，调试显示 q 是nullptr，谢谢了

 # include <malloc.h>
# include <stdlib.h>//exit
# include <stdio.h>

typedef struct Node
{
    int data;
    struct Node *next;
}Node, *LinkList;

LinkList Create_List(LinkList &L)
{
    Node *p, *q;
    int i, n;
    int data;
    L = (LinkList)malloc(sizeof(Node));
    q = L;
    printf("链表的长度为：");
    scanf_s("%d", &n);
    for (i = 0; i<n; i++)
    {
        scanf_s("%d", &data);
        p = (struct Node*)malloc(sizeof(struct Node));
        p->data = data;
        q->next = p;
        q = p;
    }
    q->next = NULL;
    return L;
}

LinkList Merge_List(LinkList La, LinkList Lb)
{
    Node *p, *q;
    LinkList L;
    L = (LinkList)malloc(sizeof(Node));
    L = NULL;
    p = La->next;
    q = Lb->next;
    while (La&&Lb)
    {
        if (La->data<Lb->data)
        {
            L = p;
            p = p->next;
        }
        else
        {
            L = q;
            q = q->next;
        }
    }
    L = p ? p : q;
    return L;
}

LinkList Reverse_List(LinkList L)
{
    Node *p, *q;
    p = L->next;
    L->next = NULL;
    while (p != NULL)
    {
        q = p->next;
        p->next = L->next;
        L->next = p;
        p = q;
    }
    return L;
}


void Print_List(LinkList L)
{
    Node *p = L->next;
    while (p != NULL)
    {
        printf("%d", p->data);
        p = p->next;
    }
    printf("\n");
}


int main()
{
    LinkList La, Lb;
    La = (LinkList)malloc(sizeof(Node));
    Lb = (LinkList)malloc(sizeof(Node));
    Create_List(La);
    Create_List(Lb);
    Print_List(Merge_List(La, Lb));
}

答

# include <malloc.h>
# include <stdlib.h>//exit
# include <stdio.h>

typedef struct Node
{
    int data;
    struct Node *next;
}Node, *LinkList;

LinkList Create_List(LinkList &L)
{
    Node *q;
    int i, n;
    int data;
    L = (LinkList)malloc(sizeof(Node));
    q = L;
    printf("链表的长度为：");
    scanf_s("%d", &n);
    for (i = 0; i<n; i++)
    {
        scanf_s("%d", &data);
        q->data = data;

        q->next = (LinkList)malloc(sizeof(struct Node));

        if (i < n - 1)
            q = q->next;
    }
    q->next = 0;
    return L;
}


LinkList Merge_List(LinkList La, LinkList Lb)
{
    LinkList p, t;
    LinkList a = La, b = Lb;
    if (La->data < Lb->data) {
        t = p = La;
        a = La->next;
    }
    else {
        t = p = Lb;
        b = Lb->next;
    }
    while (a!=NULL&&b!=NULL) {
        if (a->data < b->data) {
            t->next = a;
            a = a->next;
            t = t->next;
        }
        else {
            t->next = b;
            b = b->next;
            t = t->next;
        }
    }
    if (a == NULL) {
        t->next = b;
    }
    else {
        t->next = a;
    }
    return p;
}

LinkList Reverse_List(LinkList L)
{
    Node *p, *q;
    p = L->next;
    L->next = NULL;
    while (p != NULL)
    {
        q = p->next;
        p->next = L->next;
        L->next = p;
        p = q;
    }
    return L;
}


void Print_List(LinkList L)
{
    while (L != NULL)
    {
        printf("%d ", L->data);
        L = L->next;
    }
    printf("\n");
}


int main()
{
    LinkList La, Lb;
    La = (LinkList)malloc(sizeof(Node));
    Lb = (LinkList)malloc(sizeof(Node));
    Create_List(La);
    Create_List(Lb);
    Print_List(Merge_List(La, Lb));

    getchar();
    getchar();
}

答

代码复制的不正确吧，Merge_List里面那句La->datadata是什么

因为这个po提问平台默认使用了Markdown，建议在代码段前后加上```

这样才能看到正常代码

引发了未经处理的异常:读取访问权限冲突

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