linux C编程出了“段错误” ！！！

[windwarrior]

一个线性链表的初始化程序，运行时显示“Segmentation fault" ,代码如下：
# include <stdio.h>
# include <malloc.h>
# include <stddef.h>
# include <stdlib.h>

# define TRUE 1
# define FALSE 0
# define OK 1
# define ERROR 0
# define OVERFLOW -1

struct sqlist
{
int * p;
int length;
int listsize;
}sqlist;

int Initlist_sq(struct sqlist * L, int LIST_INIT_SIZE)
{
L->p = (int * )malloc(LIST_INIT_SIZE * sizeof(int));
if ( L->p== NULL ) exit(OVERFLOW);
L->length = 0;
L->listsize = LIST_INIT_SIZE;
return OK;
}

void main()
{
struct sqlist * p;
int status = 0;
status = Initlist_sq(p, 100);
if( status)
printf("memory allocation succeed\n");
else
printf("memory allocation failed\n");
}

[TANG_XIAO_BIN]

int Initlist_sq(struct sqlist * L, int LIST_INIT_SIZE)
{
L->p = (int * )malloc(LIST_INIT_SIZE * sizeof(int));//使用无效指针，你应该给L也分配内存
if ( L->p== NULL ) exit(OVERFLOW);
L->length = 0;
L->listsize = LIST_INIT_SIZE;
return OK;
}

void main()
{
struct sqlist * p;//是无效指针
int status = 0;
status = Initlist_sq(p, 100);
if( status)
printf("memory allocation succeed\n");
else
printf("memory allocation failed\n");
}

[windwarrior]

[Quote=引用 1 楼 tang_xiao_bin 的回复:]
int Initlist_sq(struct sqlist * L, int LIST_INIT_SIZE)
{
L->p = (int * )malloc(LIST_INIT_SIZE * sizeof(int));//使用无效指针，你应该给L也分配内存
if ( L->p== NULL ) exit(OVERFLOW);
L->length = 0;
L->listsiz……
[/Quote]
你能稍微改一下吗 我新手 不好意思

[TANG_XIAO_BIN]

# include <stdio.h>
# include <malloc.h>
# include <stddef.h>
# include <stdlib.h>

# define TRUE 1
# define FALSE 0
# define OK 1
# define ERROR 0
# define OVERFLOW -1

struct sqlist
{
int * p;
int length;
int listsize;
}sqlist;

int Initlist_sq(struct sqlist * L, int LIST_INIT_SIZE)
{
L->p = (int * )malloc(LIST_INIT_SIZE * sizeof(int));//问题就在这里出现的
if ( L->p== NULL ) exit(OVERFLOW);
L->length = 0;
L->listsize = LIST_INIT_SIZE;
return OK;
}

void main()
{
struct sqlist * p = malloc(sizeof(sqlist));//你访问的地址是无效的
int status = 0;
status = Initlist_sq(p, 100);
if( status)
printf("memory allocation succeed\n");
else
printf("memory allocation failed\n");
}

[windwarrior]

[Quote=引用 3 楼 tang_xiao_bin 的回复:]
# include <stdio.h>
# include <malloc.h>
# include <stddef.h>
# include <stdlib.h>

# define TRUE 1
# define FALSE 0
# define OK 1
# define ERROR 0
# define OVERFLOW -1

struct sqlist
{
……
[/Quote]
谢了 没有理解清楚指针 给p初始化就好了

[TANG_XIAO_BIN]

呵呵，这是因为你没有弄清楚，你分配的内存给了哪个变量，可能是一时迷糊！