Question

c语言，每步的意思

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <dos.h>
#include <conio.h>
int main()
{
struct tm *curtime;
time_t t;
clock_t start;
double th_hour,th_min,th_sec;
do
{
t=time(0);
time_t rawtime;
struct tm * timeinfo;
time ( &rawtime );
timeinfo = localtime ( &rawtime ); /*得到当前系统时间*/
printf("%.0f:",(double)timeinfo->tm_hour);
if((double)timeinfo->tm_min<10) printf("0");
printf("%.0f:",(double)timeinfo->tm_min);

if((double)timeinfo->tm_sec<10) printf("0");
printf("%.0f",(double)timeinfo->tm_sec);
printf("\n");

start=clock();
while(clock()-start<1000);
system("cls");
}while(!kbhit()); /* 按任一键退出 */
return 0;
}

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <dos.h>
#include <conio.h>
int main()
{
struct tm *curtime;
time_t t;
clock_t start;
do
{
t=time(0);
time_t rawtime;
struct tm * timeinfo;
time ( &rawtime );/*得到当前日期和时间*/
timeinfo = localtime ( &rawtime ); /*将整数格式时间转换为tm结构体时间*/
printf("%.0f:",(double)timeinfo->tm_hour);/*输出时*/
if((double)timeinfo->tm_min<10) printf("0");/*不到10分钟时两位的前一位写0*/
printf("%.0f:",(double)timeinfo->tm_min);/*输出分*/
if((double)timeinfo->tm_sec<10) printf("0");/*不到10秒钟时两位的前一位写0*/
printf("%.0f",(double)timeinfo->tm_sec);/*输出秒*/
printf("\n");
start=clock();/*从程序开始执行起到所消耗的时间*/
while(clock()-start<1000);/*等待一秒钟*/
system("cls");/*清屏*/ /*如果你不动它，则每秒钟重复一次外层while循环，即为时钟*/
}while(!kbhit()); /* 按任一键退出 */
return 0;
}

追问

什么是tm结构，还有取系统时间的原理是什么？谢谢了

追答

struct tm {
int tm_sec; /* seconds after the minute - [0,59] */
int tm_min; /* minutes after the hour - [0,59] */
int tm_hour; /* hours since midnight - [0,23] */
int tm_mday; /* day of the month - [1,31] */
int tm_mon; /* months since January - [0,11] */
int tm_year; /* years since 1900 */
int tm_wday; /* days since Sunday - [0,6] */
int tm_yday; /* days since January 1 - [0,365] */
int tm_isdst; /* daylight savings time flag */
};
转换后，数字时间值就变成了对应这些字段的值，年月日时分秒，第几周第几天还有时令信息。
得到时间的方法就是time ( &rawtime );
time函数能得到时间，就存储在 rawtime 变量中