1.格式化输出函数

2.输出日期到文本文档和数组中

#include<stdio.h>int main()
{int year=2021,month=4,date=8;FILE *fd;char buf[64];fd=fopen("data.txt","a+");fprintf(fd,"%d-%d-%d\n",year,month,date);sprintf(buf,"%d-%d-%d\n",year,month,date);int count=0;while(buf[count]!='\0'){count++;}printf("buf=%scount=%d\n",buf,count);return 0;
}

3.练习

3.1 题目

3.2 提示

3.3 实现

#include<stdio.h>
#include<unistd.h>
#include<time.h>
#include<string.h>int main()
{FILE *fp;char buf[64];int line=0;time_t t;struct tm* tp;fp=fopen("./test.txt","a+");if(fp==NULL){perror("fopen error");return -1;}while(fgets(buf,64,fp)!=NULL){if(buf[strlen(buf)-1]=='\n'){line++;}}while(1){time(&t);tp=localtime(&t);fprintf(fp,"%02d,%d-%02d-%02d %02d:%02d:%02d\n",++line,tp->tm_year+1900,tp->tm_mon+1,tp->tm_mday,tp->tm_hour,tp->tm_min,tp->tm_sec);fflush(fp);sleep(3);}fclose(fp);return 0;
}