c-使用链表实现堆栈时出现分段错误

Question

我使用一个链表来实现堆栈，因为它是在大学里给我们的，但由于我对分段错误不太了解，所以无法删除分段错误。我把我的代码放在这里。请告诉我的错误和原因，这样就不会再犯这个错误了

#include <stdio.h>
#include <stdlib.h>
struct node {   int data;   struct node *next; }; 
struct node *top = NULL;
//push function representation 
void push (int x) {   
struct node*newnode;
newnode = (struct node *) malloc (sizeof (struct node));
newnode->data = x;
newnode->next = top;
top = newnode;
}
//traverse function representation
void traverse () 
{
struct node*temp;
temp = top;
if (top == NULL)
{
printf ("Stack is empty, please push some element");
}   
else
{
while (top != NULL)
{     
printf ("The element(s) in Stack are %d", temp->data);
temp = temp->next;
}
}
}
//peek function representation 
void peek () 
{   
if (top == NULL)
{
printf ("Stack is empty");
}   
else
{
printf ("Top element is %d", top->data);
} 
}
//pop function representation 
void pop ()
{   
struct node *temp;   temp = top;   
if (top == NULL)
{
printf ("This is underflow condition");
}   
else
{
printf ("%d", top->data);
top = top->next;
free (temp);
} 
}
void main () 
{
push (2);
push (4);
traverse ();
peek ();
pop ();
}

Answer 1

traverse函数的这一部分是错误的：

while (top != NULL)  // <---- ups
{     
printf ("The element(s) in Stack are %d", temp->data);
temp = temp->next;
}

当您到达列表末尾时，temp将变为NULL，但由于您的检查是在top上完成的，您将取消引用NULL，您的程序将崩溃。

应为：

while (temp != NULL)  // <---- fixed
{     
printf ("The element(s) in Stack are %d", temp->data);
temp = temp->next;
}