Job 7.28 file IO and standard IO

1. Use standards IO complete time.txt

Request to create a time.txt, The format of storage content is as follows ：

[1] 2022-07-28 17:15:06

[2] 2022-07-28 17:15:07

[3] 2022-07-28 17:15:08

ctrl + c Exit procedure , Restart the program after a while

---

[1] 2022-07-28 17:15:06

[2] 2022-07-28 17:15:07

[3] 2022-07-28 17:15:08 <-------------------

[4] 2022-07-28 17:16:31

[5] 2022-07-28 17:16:32

Code

#include <stdio.h>
#include <unistd.h>
#include <time.h>
int main(int argc, const char *argv[])
{
    
	FILE *fp=fopen("./time.txt","a+");
	if(NULL==fp)
	{
    
		perror("fopen");
		return -1;
	}
	char a;
	int count=1;
	while((a=fgetc(fp))!=-1)
	{
    
		if(a=='\n')
		{
    
			count++;
		}
	}
	time_t t;
	struct tm *info=NULL;
	while(1)
	{
    
		t=time(NULL);
		info=localtime(&t);
		fprintf(fp,"[%02d] %d-%02d-%02d %02d:%02d:%02d\n", \
				count,info->tm_year+1900, info->tm_mon+1, info->tm_mday,\
				info->tm_hour, info->tm_min, info->tm_sec);
		count++;
		fflush(fp);
		sleep(1);
	}
	fclose(fp);
	return 0;
}

Running results

2. Required documents IO Copy a picture

Code

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#define MSG_ERR(msg) do{
       \ fprintf(stderr,"line: %d ", __LINE__); \ perror(msg);\ }while(0)

int main(int argc, const char *argv[])
{
    
	
	int fd1=open("/home/ubuntu/ picture /sllh.jpg",O_RDONLY);
	if(fd1<0)
	{
    
		MSG_ERR("open");
		return -1;
	}
	int fd2=open("./sllh.jpg",O_WRONLY|O_CREAT|O_TRUNC,0777);
	if(fd2<0)
	{
    
		MSG_ERR("open");
		return -1;
	}
	char buf[100];
	ssize_t c;
	while((c=read(fd1,buf,100))>0)
	{
    
		write(fd2,buf,c);
	}
	close(fd1);
	close(fd2);
	return 0;
}

Running results

take /home/ubuntu/ picture /sllh.jpg Copy to current directory

3. additional ： Using standard IO Copy a picture

Code

#include <stdio.h>
#define MSG_ERR(msg) do{
       \ fprintf(stderr,"line: %d ", __LINE__); \ perror(msg);\ }while(0)

int main(int argc, const char *argv[])
{
    
	
	FILE *fp1=fopen("/home/ubuntu/ picture /sllh.jpg","r");
	if(fp1<0)
	{
    
		MSG_ERR("fopen");
		return -1;
	}
	FILE *fp2=fopen("./sllh.jpg","w+");
	if(fp2<0)
	{
    
		MSG_ERR("open");
		return -1;
	}
	char buf[100];
	size_t c;
	while((c=fread(buf,1,100,fp1))>0)
	{
    
		fwrite(buf,1,c,fp2);
	}
	fclose(fp1);
	fclose(fp2);
	return 0;
}

Running results

take /home/ubuntu/ picture /sllh.jpg Copy to current directory