1> 写一个日志文件，将程序启动后，每一秒的时间写入到文件中

#include <myhead.h>
int main(int argc,const char *argv[])
{
 	FILE *fp = NULL;
 	if((fp=fopen("./log.txt","r"))==NULL)	
	{
		perror("open error1");
		return -1;
	}
	char buf[10] = "";
    int count = 0;
    while(1)
    {
        char *ptr = fgets(buf, sizeof(buf), fp);
        if(ptr == NULL)             
        {
            	break;
        }

        if(buf[strlen(buf)-1] == '\n')
        {
            count++;
        }
    }
	fclose(fp);
 	FILE *fp1 = NULL;
 	if((fp1=fopen("./log.txt","a"))==NULL)	
	{
		perror("open error2");
		return -1;
	}
	time_t sys_time = time(NULL);
	struct tm *p = localtime(&sys_time);
	int old_time = p->tm_sec;
	while(1)
	{
		time_t sys_time1 = time(NULL);
		struct tm *p1 = localtime(&sys_time1);
		if((p1->tm_sec-old_time+60)%60==1)
		{
			old_time = p1->tm_sec;
			fprintf(fp1,"%d:%4d-%2d-%2d %2d.%2d.%2d\n",count+1,p1->tm_year+1900,p1->tm_mon+1,p1->tm_mday,p1->tm_hour,p1->tm_min,p1->tm_sec);
			count++;
			fgetc(fp1);
			
		}
		
	}
	fclose(fp1);
    return 0;
}

2> 使用fread、fwrite完成两个文件的拷贝

不允许只读写一次

#include <myhead.h>
int main(int argc,const char *argv[])
{
	if(argc!=3)
	{
		perror("error");
		return -1;
	}
 	FILE *fp1 = NULL;
 	if((fp1=fopen(argv[1],"r"))==NULL)
	{
		perror("fopen error");
		return -1;
	}
 	FILE *fp2 = NULL;
 	if((fp2=fopen(argv[2],"a"))==NULL)
	{
		perror("fopen error");
		return -1;
	}	
	char buf[10]="";
	while(1)
	{
		int res=fread(buf,sizeof(buf),1,fp1);
		if(res<1)
		{
			break;
		}
		fwrite(buf,sizeof(buf),1,fp2);
	}
	fclose(fp1);
	fclose(fp2);

    return 0;
}

 

3> 实现对bmp图像的读写操作

#include<myhead.h>

int main(int argc, const char *argv[])
{
    //定义文件指针
    FILE *fp = NULL;
    if((fp = fopen("./gg.bmp", "r+")) == NULL)
    {
        perror("fopen error");
        return -1;
    }

    //获取文件大小
    int img_size = 0;

    //将文件光标偏移2个字节
    fseek(fp, 2, SEEK_SET);

    //读取4字节的内容
    fread(&img_size, sizeof(img_size), 1, fp);

    printf("size = %d\n", img_size);        //图像大小

    //从头向后偏移54字节后，就是图像数据
    fseek(fp, 54, SEEK_SET);

    //定义一个像素
    unsigned char color[3] = {0, 0, 255};     //正红色
    for(int i=0; i<960/2; i++)          //外行
    {
        for(int j=0;j<1280; j++)       //内列
        {
            fwrite(color, sizeof(color), 1, fp);
        }
    }
    
    //关闭文件
    fclose(fp);

    return 0;
}

 

思维导图