为什么已经用malloc分配空间了还是显示异常访问冲突

Question

#include"stdio.h"
#include"stdlib.h"
typedef struct node
{
    int data;//结点所对应的数据
    struct node* Next;//指向下一个结点的指针next
}l, * list;
list H;
list makebiao(int n)//n为元素个数
{
    int i;
    list H;
    H = (list)malloc(sizeof(l));
    H->Next= (list)malloc(sizeof(l));
    H->data = 0;
    list p = H->Next;
    p->Next= (list)malloc(sizeof(l));
    for (i = 1; i < n; i++)
    {
        p->data = i;
        p = p->Next;
    }
    return H;
}
void destroy(list* H)
{
    list p, q;
    p = *H;
    while (p)
    {
        q = p;
        p = p->Next;
        free(q);
    }
    *H = NULL;
}
list insert(list H, int x)
{
    list p, q;
    p = (list)malloc(sizeof(l));
    q = (list)malloc(sizeof(l));
    for (p = H; p->Next->data <= x; p = p->Next)
    {
    }
    q->data = x;
    q->Next = p->Next;
    q = p->Next;
    return H;
}
void putbiao(list H)
{

    while (H)
    {
        printf("%d\t", H->data);
        H = H->Next;
    }
}
int main()
{

    list H;
    H = makebiao(99);
    putbiao(H);
    insert(H, 5);
    putbiao(H);
    destroy(&H);
            return 1;
}

报错图片

用的是VS2019

Answer 1

修改如下，改动处见注释，供参考：

#include"stdio.h"
#include"stdlib.h"
typedef struct node
{
    int data;//结点所对应的数据
    struct node* Next;//指向下一个结点的指针next
}l, * list;
list H;
list makebiao(int n)//n为元素个数
{
    int i;
    list H;
    H = (list)malloc(sizeof(l));
    H->Next = NULL;  //H->Next= (list)malloc(sizeof(l)); 修改
    H->data = 0;
    list p = H;      // list p = H->Next;                修改
                     //p->Next= (list)malloc(sizeof(l)); 修改
    for (i = 1; i <= n; i++) // for (i = 1; i < n; i++)  修改
    {
        p->Next = (list)malloc(sizeof(l));
        p->Next->Next = NULL;
        p->Next->data = i;
        p = p->Next;
    }
    return H;
}
void destroy(list* H)
{
    list p, q;
    p = *H;
    while (p)
    {
        q = p;
        p = p->Next;
        free(q);
    }
    *H = NULL;
}
list insert(list H, int x)
{
    list p, q;
    p = NULL;     //p = (list)malloc(sizeof(l));   修改
    q = (list)malloc(sizeof(l));
    q->data = x;
    for (p = H; p->Next && p->Next->data <= x; p = p->Next); // 修改
    // for (p = H; p->Next->data <= x; p = p->Next)
    q->Next = p->Next;
    p->Next = q; //q = p->Next;  修改
    return H;
}
void putbiao(list H)
{
    H = H->Next; // 修改
    while (H)
    {
        printf("%d\t", H->data);
        H = H->Next;
    }
}
int main()
{
 
    list H;
    H = makebiao(99);
    putbiao(H);
    insert(H, 5);
    putbiao(H);
    destroy(&H);
    return 1;
}