An not handle exception: Read rights conflict, Pointer value out of limit - c++

Question

void TableInsert(SLinkListType &L, RedType d[], int n)
/* 由数组D建立n个元素的表插入排序的静态链表L */
{
int i, p, q;
L.r[0].rc.key = INT_MAX;
L.r[0].next = 0;
for (i = 0; i < n; i++)
{
L.r[i + 1].rc = d[i];
q = 0;
p = L.r[0].next;
while (L.r[p].rc.key <= L.r[i + 1].rc.key)
{
q = p;
p = L.r[p].next;
}
L.r[i + 1].next = p;
L.r[q].next = i + 1;
}
L.length = n;
}//TableInsert
void Arrange(SLinkListType &L)
{
int i, p, q;
SLNode t;
p = L.r[0].next;
for (i = 1; i < L.length; i++)
{
while (p < i)
p = L.r[p].next;
q = L.r[p].next;
if (p != i)
{
t = L.r[p]; /* 交换记录，使第i个记录到位 */
L.r[p] = L.r[i];
L.r[i] = t;
L.r[i].next = p;
}
p = q; /* p指示尚未调整的表尾，为找第i+1个记录作准备 */
}
}//Arrange
void Sort(SLinkListType L, int adr[])
/* 求得adr[1..L.length]，adr[i]为静态链表L的第i个最小记录的序号 */
{
int i = 1, p = L.r[0].next;
while (p)
{
adr[i++];
p = L.r[p].next;
}
}//Sort
void ReArrange(SLinkListType &L, int adr[])
/* adr给出静态链表L的有序次序，即L.r[adr[i]]是第i小的记录。 */
{
int i, j, k = 0;
for (i = 1; i < L.length; i++)
{
if (adr[i] != i)
{
j = i;
L.r[0] = L.r[i];
while (adr[j] != i)
/* 调整(*L).r[adr[j]]的记录到位直到adr[j]=i为止 */
{
k = adr[j];
printf("%d", k);
/* 如：adr[1] = 6，则 K = 6，将 r[6] 赋值到 r[1], 同时同步adr[], 然后将 adr[1] 移动 adr[6]*/
L.r[j] = L.r[k]; /* L.r[j] = L.r[adr[j]] */
adr[j] = j;
j = k; /* 记录按序到位 */
}
L.r[j] = L.r[0]; /* L.r[6] = L.r[0] */
adr[j] = j; /* 同步 adr[] */
}
}
}//ReArrange
void Print(SLinkListType L)
{
int i;
for (i = 1; i <= L.length; i++)
{
printf("key=%d ord=%d next=%d\n", L.r[i].rc.key, L.r[i].rc.otherinfo, L.r[i].next);
}
}//Print
#define N 8
void main()
{
RedType d[N] = { {49,1},{38,2},{65,3},{97,4},{76,5},{13,6},{27,7},{49,8} };
SLinkListType a, b;
int *adr = NULL, i = 0; /* 内存分配有误，adr 的值超出范围 */
TableInsert(a, d, N);
b = a; /* 复制静态链表l2与l1相同 */
printf("排序前:\n");
Print(a);
Arrange(a);
printf("a排序后:\n");
Print(a);
adr = (int *)malloc((b.length + 1) * sizeof(int));
Sort(b, adr);
for (i = 1; i <= b.length; ++i)
{
printf("adr[%d] = %d", i, adr[i]);
}
printf("\n");
ReArrange(b, adr);
printf("b排序后:\n");
Print(b);
}
why when i defined int *adr = NULL i already let it equal NULL, but the value of adr out of the limit, and get an error: the Read rights conflict, how to define a pointer variable, so that the system don`t distribution a unknown pointer value. if define a NULL pointer, what is the pointer value , is my initialization was wrong? how to initialization a pointer

Answer 1

If I understand you correctly, you're stepping through the code in a debugger, and stopped at the line
int *adr = NULL, i = 0;
and wonder why adr is not a null pointer?
Then that's because the initialization haven't happened yet. If you take one more step then the initialization will happen and adr should become NULL.

Answer 2

Instead of " int *adr = NULL; , try to use
int *adr
adr = new int;
If you use int *adr = NULL , it will cause to create an insufficient memory .
adr = new int; - creates new dynamic memory. NULL is used to after deleting pointer !!!