学习IO的第五天

作业：使用两个线程完成文件的拷贝写入，分线程1写入前半段，分线程2写入后半段，主线程用来回收资源

#include <head.h>void *sork(void *arg);
void *sork2(void *arg);int file_copy(int start,int len)   //拷贝的函数
{int rd = -1;int wd = -1;if((rd = open("./01_test.c",O_RDONLY)) == -1){printf("open_r error\n");}if((wd = open("./text.txt",O_WRONLY)) == -1){printf("open_w error\n");}lseek(rd,start,SEEK_SET);lseek(wd,start,SEEK_SET);char buf[128]="";int count = 0;while(1){int res = read(rd,buf,sizeof(buf));count += res;if(count >= len || res == 0){write(wd,buf,res-(count-len));break;}write(wd,buf,res);}close(rd);close(wd);}int length()
{int rd = -1;int wd = -1;if((rd = open("./01_test.c",O_RDONLY)) == -1){perror("open_r error\n");return -1;}if((wd = open("./text.txt",O_WRONLY|O_CREAT|O_TRUNC,0664) == -1)){perror("open_w error\n");return -1;}int len = lseek(rd,0,SEEK_END);close(rd);close(wd);return len;
}int main(int argc, const char *argv[])
{pthread_t tid = -1;pthread_t tid2 = -1;int len = length();   //获取文件大小if(pthread_create(&tid, NULL, sork, &len) != 0) //创建线程1{printf("创建线程失败\n");return -1;}if(pthread_create(&tid2, NULL, sork2, &len) != 0) //创建线程2{printf("创建线程失败\n");return -1;}pthread_join(tid,NULL);pthread_join(tid2,NULL);printf("已回收分线程资源\n");return 0;
}void *sork(void *arg)  //分支线程1
{int len = *(int *)arg;   file_copy(0,len/2);   //调用拷贝的函数printf("分支线程1退出\n");pthread_exit(NULL);
}void *sork2(void *arg)  //分支线程2
{int len = *(int *)arg;file_copy(len/2,len-len/2);   //调用拷贝的函数printf("分支线程2退出\n");pthread_exit(NULL);
}

结果

不调函数，一样

#include <head.h>void *sork(void *arg);
void *sork2(void *arg);int length()
{int rd = -1;int wd = -1;if((rd = open("./01_test.c",O_RDONLY)) == -1){perror("open_r error\n");return -1;}if((wd = open("./text.txt",O_WRONLY|O_CREAT|O_TRUNC,0664) == -1)){perror("open_w error\n");return -1;}int len = lseek(rd,0,SEEK_END);close(rd);close(wd);return len;
}int main(int argc, const char *argv[])
{pthread_t tid = -1;pthread_t tid2 = -1;int len = length();if(pthread_create(&tid, NULL, sork, &len) != 0) //创建线程1{printf("创建线程失败\n");return -1;}if(pthread_create(&tid2, NULL, sork2, &len) != 0) //创建线程2{printf("创建线程失败\n");return -1;}pthread_join(tid,NULL);pthread_join(tid2,NULL);return 0;
}void *sork(void *arg)  //分支线程1
{int len = *(int *)arg;int rd = -1;int wd = -1;printf("进入分支线程1\n");if((rd = open("./01_test.c",O_RDONLY)) == -1){printf("open_r error\n");}if((wd = open("./text.txt",O_WRONLY)) == -1){printf("open_w error\n");}lseek(rd,0,SEEK_SET);lseek(wd,0,SEEK_SET);char buf[128]="";int count = 0;while(1){int res = read(rd,buf,sizeof(buf));count += res;if(count >= len/2 || res == 0){write(wd,buf,res-(count-len/2));break;}write(wd,buf,res);}close(rd);close(wd);pthread_exit(NULL);
}void *sork2(void *arg)  //分支线程2
{int len = *(int *)arg;int rd = -1;int wd = -1;printf("进入分支线程2\n");if((rd = open("./01_test.c",O_RDONLY)) == -1){printf("open_r error\n");}if((wd = open("./text.txt",O_WRONLY)) == -1){printf("open_w error\n");}lseek(rd,len/2,SEEK_SET);lseek(wd,len/2,SEEK_SET);char buf[128]="";int count = 0;while(1){int res = read(rd,buf,sizeof(buf));if(res == 0){break;}write(wd,buf,res);}close(rd);close(wd);pthread_exit(NULL);}

思维导图