線程題--拆分檔案

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將一個檔案的前一半複製到一個檔案，後一半複製到另一個檔案，通過兩個線程：

 1 #include<stdio.h> 2 #include<semaphore.h> 3  4 #include<pthread.h> 5  6 FILE *fs,*fd1,*fd2; 7  8 sem_t sem1,sem2; 定義訊號變數 9 10 void *thread_handler1(void *arg)11 {12     char c;13     int count=0;14     sem_wait(&sem1);15     printf("%d\n",*((int *)arg));16    //this from https://i.cnblogs.com/EditPosts.aspx?opt=1
　　　　 while((c = fgetc(fs)) > 0)17     {18         fputc(c,fd1);19         if(++count >= *((int *)arg))判斷是否複製到中間20             break;21     }22     fclose(fd1);23 24     sem_post(&sem2);25 }26 27 void *thread_handler2(void *arg)28 {29     char c;30 //    fseek();31     sem_wait(&sem2);32     printf("enter\n");33     while((c = fgetc(fs)) > 0)34     {35         fputc(c,fd2);36     }37     fclose(fd2);38 }39 40 int main(int argc, const char *argv[])41 {42     pthread_t thread1,thread2;定義線程變數43 44     fs = fopen("copy_half.c","r");45     fd1 = fopen("text1.txt","w");開啟檔案46     fd2 = fopen("text2.txt","w");47     int middle,i;48     fseek(fs,0,SEEK_END);49     i = ftell(fs);50     middle = i/2;51     fseek(fs,0,SEEK_SET);52 　　//from  https://i.cnblogs.com/EditPosts.aspx?opt=153     sem_init(&sem1,0,1);54     sem_init(&sem2,0,0);55     pthread_create(&thread1,NULL,thread_handler1,(void *)&middle);開第一個線程56     pthread_create(&thread2,NULL,thread_handler2,(void *)&middle);開第二個線程57 58     pthread_join(thread1,NULL);等待線程結束59     pthread_join(thread2,NULL);60 61     sem_destroy(&sem1);銷毀訊號量62     sem_destroy(&sem2);63     64 65 66     return 0;67 }

 

線程題--拆分檔案