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