代码练习

使用fread和fwrite完成两个文件的拷贝

#include<myhead.h>

int main(int argc, const char *argv[])
{

    FILE *fp = NULL;
    //重新以只读的形式打开文件
    if((fp = fopen("./OIP-C.bmp", "r")) == NULL)
    {
        perror("fopen error");
        return -1;
    }
	FILE *fp1=NULL;
	if((fp1=fopen("./text.bmp","w"))==NULL)
	{
		perror("fopen error");
		return -1;
	}

    char head[54]="";
	unsigned char color[3];
    fread(head, sizeof(head), 1, fp); //读取头
    fwrite(head, sizeof(head), 1, fp1);//写入头
	while(fread(color,sizeof(char),3,fp)==3)//读取像素点
	{
		fwrite(color,sizeof(char),3,fp1);//写入像素点
	}

    //关闭文件
    fclose(fp);
	fclose(fp1);

    return 0;
}

效果图

使用read、write完成两个文件的拷贝

#include<myhead.h>

int main(int argc, const char *argv[])
{
    //定义文件描述符变量
    int fd = -1;
    if((fd = open("./text.bmp", O_RDONLY)) == -1)
    {
        perror("open error");
        return -1;
    }
	int fd1=-1;
	if((fd1=open("./work3.bmp",O_WRONLY))==-1)
	{
		perror("open error");
		return -1;
	}

    char head[54]="";
	unsigned char color[3]="";
    lseek(fd, 0, SEEK_SET);        //将光标移到开头
    read(fd,head, 54);//读取头
	write(fd1,head,54);//写入头



    //将光标偏移到矩阵部分
    lseek(fd, 54, SEEK_SET);
	while(read(fd,color,sizeof(color))==3)//读取像素
	{
		write(fd1,color,sizeof(color));//写入像素
	}



    //关闭文件
    close(fd);
	close(fd1);

    return 0;
}

 效果图

将时间在文件中跑起来

#include <myhead.h>
//将时间在文件中跑起来
int main(int argc, const char *argv[])
{
	//打开时间文件
	FILE *fp=NULL;
	if((fp=fopen("./time.txt","a+"))==NULL)
	{
		perror("fopen error");
		return -1;
	}
	//循环计算已有行号
	int line=1;
	while(1)
	{
		char c=fgetc(fp);
		if(c=='\n')
			line++;
		if(c==EOF)
			break;
	}
	//判断新旧时间
	char time_buf[128]="";
	struct tm *t;
	time_t Old_Time,sysTime;
	while(1)
	{
		sysTime=time(NULL);
		if(Old_Time!=sysTime)
		{
			Old_Time=sysTime;
			t=localtime(&sysTime);
			snprintf(time_buf,sizeof(time_buf),"%d:%2d:%2d:%2d\n",\
					line,t->tm_hour,t->tm_min,t->tm_sec);
			printf("%s",time_buf);
			fputs(time_buf,fp);
			line++;
			fflush(fp);
		}
	}
	fclose(fp);
	return 0;
}

效果图

思维导图