C语言文件定时写入删除数据编程

C语言文件定时写入删除数据编程
#include<stdio.h>
#include<unistd.h>
#include<signal.h>
#include<stdlib.h>
#include<string.h>
#include<time.h>
#include<sys/time.h>
#include<pthread.h>
#define PERRNUM(ret, str)\
if(ret > 0)\
{\
printf("%s:%s\n", str, strerror(ret));\
exit(1);\
}
static char msg[]="time is out\n";
pthread_mutex_t mutex;
void prompt_info()
{
FILE *fp=NULL;
fp=fopen("data.txt","a+");
if(fp == NULL)
{
perror("fopen");
exit(1);
}
fseek(fp,0,2);
fputs(msg,fp);
fclose(fp);
printf("---%s",msg);
}
void delone()
{
FILE *f1;
long length;//文件总长度
char *f2;//用于记录要保存的内容
char s[100],line[100];//用于保存每次读取的一行内容
int n,lines=0;
memset(s,'\0',sizeof(char)*100);
memset(line,'\0',sizeof(char)*100);
f1=fopen("data.txt","r");//以读的方式打开文件
fseek(f1,0,2);//文件指针移到文件尾
length=ftell(f1);//取得文件长度
f2=(char *)malloc(sizeof(char)*length);//给f2分配文件长度的空间rewind(f1);//文件指针回到文件头
while(!feof(f1))
{
fgets(line,256,f1);
lines++;
}
rewind(f1);
for(n=0;n<lines;n++)
{
fgets(s,100,f1);
if(n<lines-12)
continue;
strcat(f2,s);
}
fclose(f1);
f1=fopen("data.txt","w");//重新以写的方式打开文件
fputs(f2,f1);//把保存的信息重新存储到文件当中
free(f2);
f2=NULL;
fclose(f1);
}
void deles()
{
FILE *f1;
long length;
char *f2;
char s[100],line[100];
int n,lines=0;
memset(s,'\0',sizeof(char)*100);
memset(line,'\0',sizeof(char)*100);
f1=fopen("data.txt","r");
fseek(f1,0,2);
length=ftell(f1);
f2=(char *)malloc(sizeof(char)*length);
*f2=0;
rewind(f1);
while(!feof(f1))
{
fgets(line,256,f1);
lines++;
}
if(lines>12)
{
rewind(f1);
for(n=0;n<lines;n++)
{
fgets(s,100,f1);
if(n<lines-12)
continue;
strcat(f2,s);
}
fclose(f1);
f1=fopen("data.txt","w");
fputs(f2,f1);
}
free(f2);
f2=NULL;
fclose(f1);
}
void * fun1(void *arg)
{
deles();
while(1)
{
pthread_mutex_lock(&mutex);
prompt_info();
pthread_mutex_unlock(&mutex);
sleep(1);
}
return NULL;
}
void * fun2(void *arg)
{
const unsigned int m=12;
sleep(m);
while(1)
{
printf("===%s\n",msg);
pthread_mutex_lock(&mutex);
delone();
pthread_mutex_unlock(&mutex);
sleep(4);
}
return NULL;
}
int main()
{
pthread_t tid_a,tid_b;
void *retval;
int ret1,ret2;
pthread_mutex_init(&mutex,NULL);
ret1 = pthread_create(&tid_a, NULL, fun1, NULL);
PERRNUM(ret1, "pthread_create1");
ret2 = pthread_create(&tid_b, NULL, fun2, NULL);
PERRNUM(ret2, "pthread_create2");
pthread_join(tid_a, &retval);
pthread_join(tid_b, &retval);
pthread_mutex_destroy(&mutex);
return 0;
}。