## gmtime ##
取得目前时间和日期
### 相关函数 ###
time,asctime,ctime,localtime
### 表头文件 ###
```
#include<time.h>
```
### 定义函数 ###
```
struct tm *gmtime(const time_t *timep);
```
### 函数说明 ###
gmtime()将参数timep 所指的time_t 结构中的信息转换成真实世界所使用的时间日期表示方法,然后将结果由结构tm返回。
结构tm的定义为
```
struct tm
{
int tm_sec;
int tm_min;
int tm_hour;
int tm_mday;
int tm_mon;
int tm_year;
int tm_wday;
int tm_yday;
int tm_isdst;
};
```
int tm_sec 代表目前秒数,正常范围为0-59,但允许至61秒
int tm_min 代表目前分数,范围0-59
int tm_hour 从午夜算起的时数,范围为0-23
int tm_mday 目前月份的日数,范围01-31
int tm_mon 代表目前月份,从一月算起,范围从0-11
int tm_year 从1900 年算起至今的年数
int tm_wday 一星期的日数,从星期一算起,范围为0-6
int tm_yday 从今年1月1日算起至今的天数,范围为0-365
int tm_isdst 日光节约时间的旗标
此函数返回的时间日期未经时区转换,而是UTC时间。
### 返回值 ###
返回结构tm代表目前UTC 时间
### 范例 ###
```
#include <time.h>
main(){
char *wday[]={"Sun","Mon","Tue","Wed","Thu","Fri","Sat"};
time_t timep;
struct tm *p;
time(&timep);
p=gmtime(&timep);
printf(“%d%d%d”,(1900+p->tm_year), (1+p->tm_mon),p->tm_mday);
printf(“%s%d;%d;%d\n”, wday[p->tm_wday], p->tm_hour, p->tm_min, p->tm_sec);
}
```
### 执行 ###
```
2000/10/28 Sat 8:15:38
```
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