在linux下用C语言写的关于数据文件插入操作的简单程序，运行有问题。。
如题，编译可以通过，运行不对，，代码如下：
程序代码：
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#define TM_L 14
typedef struct _calllist calllist;
struct _calllist
{
long id;
int type;
long telnum;
char btime[TM_L];
long tcount;
float charge_rate;
float charge_sum;
};
typedef struct _calllist calllist;
int selectdb(calllist **cl,int f)
{
printf ("hehihei");
int i = sizeof(calllist);
long length = lseek(f,0,SEEK_END);
if (length < i)
{
puts("empty");
return -1;
}
if (*cl != NULL)
{
free(*cl);
}
*cl = malloc(length);
lseek(f,0,SEEK_SET);
if (read(f, *cl, length) != length)
{
perror("error");
return -2;
}
printf ("haha");
return 0;
}
int insertdb(calllist * cr,int f,calllist *cl)
{
printf ("dfjdk");
int i;
i = sizeof(calllist);
int length = lseek(f,0,SEEK_END);
cr -> id = (cl + length/i - 1) -> id + 1;
printf ("1");
lseek(f,0,SEEK_END);
if (write(f,cr,i) != i)
{
perror("error");
return -1;
}
printf ("4");
return 0;
}
void printdb(calllist * cl,int f)
{
int i = sizeof(calllist);
long length = lseek(f,0,SEEK_END);
int j;
char btime[TM_L + 1] = {0};
for (j = 0; j<length/i; j++)
{
memcpy(btime, (cl+j) -> btime,TM_L);
printf ("ahha");
printf ("%ld,%d,%ld,%14s,%ld,%1.2f,%1.2f\n",
(cl+j) -> id,
(cl+j) -> type,
(cl+j) -> telnum,
btime,
(cl+j) -> tcount,
(cl+j) -> charge_rate,
(cl+j) -> charge_sum);
}
}
int main()
{
int f;
int res;
calllist cr = {1,0,12354,"34343434343444",30,3.55,3.44};
calllist *cl;
cl = NULL;
f = open("listdb",O_RDWR | O_CREAT,0664);
if (f == -1)
{
perror("error");
return 1;
}
puts("the original file:");
res = selectdb(&cl,f);
if (res == -2)
{
return 1;
}
else if(res == 0)
{
printdb(cl,f);
}
puts("insert hou file:");
insertdb(&cr,f,cl);
printf ("djfkd");
res = selectdb(&cl,f);
if (res == -2)
{
return 1;
}
else if(res == 0)
{
printdb(cl,f);
}
close(f);
return 0;
}
运行显示：Segmentation fault（core dumped），应该是insert函数不对，这是为什么啊，，希望大家帮忙看看
