1> 使用fread和fwrite完成两个文件的拷贝，要求源文件和目标文件由外界输入

#include <myhead.h>
typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;
int main(int argc, const char *argv[])
{
	//以读的形式打开要复制的文件
	FILE* rfp = fopen(argv[1],"r");
	if(NULL == rfp){
		perror("err:");
	}
	//以写的形式打开复制生成的文件
	FILE* wfp = fopen(argv[2],"w");
	if(NULL == wfp){
		perror("err:");
	}
	char rarr="";
	while(1){
		int res = fread(&rarr,1,1,rfp);//循环读取要复制的文件的内容并赋值给ch
		if(0 == res)break;              //文件读取完毕跳出循环
		fwrite(&rarr,1,1,wfp);          // 将读取到的文件内容写入到新文件
	}
	fclose(rfp);           //关闭文件描述符
	fclose(wfp);
	return 0;
}

2> 使用fgets获取当前文件的总行数

#include <myhead.h>
typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;
int main(int argc, const char *argv[])
{
	//以读的形式打开要复制的文件
	FILE* rfp = fopen(argv[1],"r");
	if(NULL == rfp){
		perror("err:");
	}
	//以写的形式打开复制生成的文件
	FILE* wfp = fopen(argv[2],"w");
	if(NULL == wfp){
		perror("err:");
	}
	char rarr[20]="";   //存放读取到的数据
	int count = 0;      //计算行数
	while(1){
		char*res = fgets(rarr,sizeof(rarr),rfp);//循环读取要复制的文件的内容
		if(res==NULL)break;
		if(rarr[strlen(rarr)-1]=='\n'){  //遇到换行符，count++，统计行数
			count++;
		//	rarr[strlen(rarr)-1] = 0;
		}
		fputs(rarr,wfp);//将读取到的文件内容写入到新文件
	}
	printf("%d",count);   //输出行数
	fclose(rfp);  //关闭文件
	fclose(wfp);
	return 0;
}

3> 向文件中每一秒打印当前系统时间

#include <myhead.h>
#include<time.h>
typedef struct sockaddr_in addr_in_t;
typedef struct sockaddr addr_t;
typedef struct sockaddr_un addr_un_t;
int main(int argc, const char *argv[])
{
	int count = 0;  //统计行数
	time_t t_sec1;  //标记时间，实现一秒输出一次
	FILE* fp = fopen("123.txt","a");
	//获取文件中的行数，实现下次此运行后不从零开始
	FILE* rfp = fopen("123.txt","r");
	while(1){
		char ch = fgetc(rfp);
		if(ch == '\n')count++;
		if(ch==EOF)break;
	}

	while(1){
		time_t t_sec = time(NULL);
		struct tm *tm_t=localtime(&t_sec);
		if(t_sec1!=t_sec){
			//将时间输出到终端
			printf("%2d  %4d-%2d-%2d  %2d:%2d:%2d\n",count,tm_t->tm_year+1900,tm_t->tm_mon+1,tm_t->tm_mday,tm_t->tm_hour,tm_t->tm_min,tm_t->tm_sec);
			//将文件输出到文件
			fprintf(fp,"%2d  %4d-%2d-%2d  %2d:%2d:%2d\n",count,tm_t->tm_year+1900,tm_t->tm_mon+1,tm_t->tm_mday,tm_t->tm_hour,tm_t->tm_min,tm_t->tm_sec);
			//每输出一次行数加一
			count++;
			//手动刷新缓存区
			fflush(fp);
		}
		//使标记时间等于最新的时间
		t_sec1 = t_sec;
	}
	return 0;
}