线程题--拆分文件

将一个文件的前一半复制到一个文件，后一半复制到另一个文件，通过两个线程：

#include<stdio.h>
#include<semaphore.h>

#include<pthread.h>

FILE *fs,*fd1,*fd2;

sem_t sem1,sem2; 定义信号变量

void *thread_handler1(void *arg)
{
    char c;
    int count=0;
    sem_wait(&sem1);
    printf("%d
",*((int *)arg));
   //this from https://i.cnblogs.com/EditPosts.aspx?opt=1
　　　　 while((c = fgetc(fs)) > 0)
    {
        fputc(c,fd1);
        if(++count >= *((int *)arg))判断是否复制到中间
            break;
    }
    fclose(fd1);

    sem_post(&sem2);
}

void *thread_handler2(void *arg)
{
    char c;
//    fseek();
    sem_wait(&sem2);
    printf("enter
");
    while((c = fgetc(fs)) > 0)
    {
        fputc(c,fd2);
    }
    fclose(fd2);
}

int main(int argc, const char *argv[])
{
    pthread_t thread1,thread2;定义线程变量

    fs = fopen("copy_half.c","r");
    fd1 = fopen("text1.txt","w");打开文件
    fd2 = fopen("text2.txt","w");
    int middle,i;
    fseek(fs,0,SEEK_END);
    i = ftell(fs);
    middle = i/2;
    fseek(fs,0,SEEK_SET);
　　//from  https://i.cnblogs.com/EditPosts.aspx?opt=1
    sem_init(&sem1,0,1);
    sem_init(&sem2,0,0);
    pthread_create(&thread1,NULL,thread_handler1,(void *)&middle);开第一个线程
    pthread_create(&thread2,NULL,thread_handler2,(void *)&middle);开第二个线程

    pthread_join(thread1,NULL);等待线程结束
    pthread_join(thread2,NULL);

    sem_destroy(&sem1);销毁信号量
    sem_destroy(&sem2);
    


    return 0;
}