1、使用fgets统计一个文件的行号

#include <stdio.h>
#include<string.h>
#include<stdlib.h>
int main(int argc, const char *argv[])
{
	FILE *fp=NULL;
	if((fp=fopen("1.c","r"))==NULL)
	{
		return -1;
	}
	int count=0;

	char buf;
	while(buf!=EOF)
	{
		buf=fgetc(fp);
		if(buf=='\n')
		{
			count++;
		}
	}
	printf("%d行\n",count);
	fclose(fp);
	return 0;
}

 2、使用fgets、fputs3完成两个文件的拷贝

#include <stdio.h>
#include<string.h>
#include<stdlib.h>
int main(int argc, const char *argv[])
{
	if(argc>2)
	{
		return 0;
	}
	FILE *fp1=NULL;
	FILE *fp2=NULL;
	//定义两个文件指针，一个读一个写
	if((fp1=fopen(argv[1],"r"))==NULL)
	{
		return -1;
	}
	if((fp2=fopen(argv[2],"w"))==NULL)
	{
		return -1;
	}
	char buf=0;
	while((buf=fgetc(fp1))!=EOF)
	{
		fputc(buf,fp2);
	}
	fclose(fp1);
	fclose(fp2);
	return 0;
}

3、向文件中输出当前的系统时间.

#include <stdio.h>
#include<string.h>
#include<stdlib.h>
#include <time.h>
#include<unistd.h>
int main(int argc, const char *argv[])
{
	while(1)
	{
		FILE *fp1=NULL;
		//定义一个数行
		if((fp1=fopen("time","r"))==NULL)
		{
			return -1;
		}
		//定义一个打印的指针
		FILE *fp2=NULL;
		if((fp2=fopen("./time","a"))==NULL)
		{
			return -1;
		}
 
		char temp;
		int num=0;
		while((temp=fgetc(fp1))!=EOF)
		{
			if(temp=='\n')
			{
				num++;
			}
		}
		time_t sys_time;
		sys_time=time(NULL);
		struct tm *t=localtime(&sys_time);
		char buf[100];
		int sec=t->tm_sec;
		sprintf(buf,"%02d、%04d-%02d-%02d  %02d:%02d:%02d\n",num,t->tm_year+1900,t->tm_mon+1,t->tm_mday,t->tm_hour,t->tm_min,t->tm_sec);
		fputs(buf,fp2);
		sleep(1);
		fclose(fp1);
		fclose(fp2);
	}
	return 0;
}