我正在做一些简单的事情,所以希望这个问题可以很容易地回答。我使用gcc编译。推送工作非常好。问题是流行。每当我编译和运行它时,我都会遇到分段错误。C中的链接堆栈Pop导致分段错误,但Push不行!
这里是流行音乐和推功能:
int push(stack *stk, int data)
{
stk->head = makeNode(data, stk->head);
stk->length += 1;
return data;
}
int pop(stack *stk)
{
//Returns popped item
//Returns -1 if stack length is zero
if (stk->length < 1)
{
printf("No items to pop.");
return -1;
}
int data = stk->head->value;
struct node *toBeFreed = stk->head;
stk->head = stk->head->ptr;
free(toBeFreed);
stk->length -= 1;
return data;
}
老实说,我不知道是什么问题,因为代码是相似的。我在推送函数中重新分配堆栈中的头部变量,但会导致pop函数中的错误。数据分配也给我一个seg故障。除了返回和堆栈长度赋值语句之外,几乎所有东西都会导致分段错误。你们能帮助我弄清楚吗?什么导致这些seg故障?
这里是整个程序:
#include <stdio.h>
#include <stdlib.h>
struct node
{
int value;
struct node *ptr;
};
struct node *makeNode(int value, struct node *ptr)
{
struct node *newNode = malloc(sizeof(struct node));
newNode->value = value;
newNode->ptr = ptr;
return ptr;
}
typedef struct stack
{
struct node *head;
int length;
} stack;
stack makeStack()
{
stack stk;
stk.head=NULL;
stk.length = 0;
return stk;
}
int push(stack *stk, int data)
{
stk->head = makeNode(data, stk->head);
stk->length += 1;
return data;
}
int pop(stack *stk)
{
if (stk->length < 1)
{
printf("No items to pop.");
return -1;
}
int data = stk->head->value;
struct node *toBeFreed = stk->head;
stk->head = stk->head->ptr;
free(toBeFreed);
stk->length -= 1;
return data;
}
int main()
{
stack s = makeStack();
printf("Pushing ints one through five. Should display ints one through five on separate lines: \n");
int i;
for (i = 1; i <= 5; i++)
printf("%d\n",push(&s, i));
printf("Popping ten values. Should display ints one through five in reverse order on separate lines along with 5 error statements.\n");
for (i = 0; i <= 10; i++)
printf("%d\n",pop(&s));
return 0;
}
非常感谢!这完全解决了一切! – 2010-07-08 17:49:23
@caf:在makeStack中,他没有返回任何地址。他正在返回一个局部变量的值,这是完全有效的。 – sepp2k 2010-07-09 10:18:35