gmtime
gmtime()是把日期和时间转换为格林威治(GMT)时间的函数
头文件:TIME.H
原形:struct tm *gmtime(long *clock);
例:
#include "stdio.h"
#include "time.h"
#include "stdlib.h"
int main(void)
{
time_t t;
struct tm *gmt, *area;
tzset(); /* tzset()*/
t = time(NULL);
area = localtime(&t);
printf("Local time is: %s", asctime(area));
gmt = gmtime(&t);
printf("GMT is: %s", asctime(gmt));
return 0;
}
localtime和gmtime这两个函数采用了time.h中的一个tm结构体：
struct tm
{
int tm_sec; /* Seconds. [0-60] (1 leap second) */
int tm_min; /* Minutes. [0-59] */
int tm_hour; /* Hours. [0-23] */
int tm_mday; /* Day. [1-31] */
int tm_mon; /* Month. [0-11] */
int tm_year; /* Year - 1900. */
int tm_wday; /* Day of week. [0-6] */
int tm_yday; /* Days in year.[0-365] */
int tm_isdst; /* DST. [-1/0/1]*/
#ifdef __USE_BSD
long int tm_gmtoff; /* Seconds east of UTC. */
__const char *tm_zone; /* Timezone abbreviation. */
#else
long int __tm_gmtoff; /* Seconds east of UTC. */
__const char *__tm_zone; /* Timezone abbreviation. */
#endif
};
这两个函数的原型为：
struct tm *localtime(const time_t *timep);
struct tm *gmtime(const time_t *timep);
具体实现为：
localtime.c
---------------------------------------------------------
#include <stdio.h>
#include <time.h>
void cur_time(void);
int main(int argc,char **argv)
{
cur_time();
return 0;
}
void cur_time(void)
{
char *wday[]={"星期天","星期一","星期二","星期三","星期四","星期五","星期六"};
time_t timep;
struct tm *p;
time(&timep);
p=localtime(&timep); /* 获取当前时间 */
printf("%d年%02d月%02d日",(1900+p->tm_year),(1+p->tm_mon),p->tm_mday);
printf("%s %02d:%02d:%02d
",wday[p->tm_wday],p->tm_hour,p->tm_min,p->tm_sec);
}
---------------------------------------------------------
gcc localtime.c 后运行a.out结果为：
2007年12月26日星期三 11:07:15
gmtime.c
---------------------------------------------------------
#include <stdio.h>
#include <time.h>
void cur_time(void);
int main(int argc,char **argv)
{
cur_time();
return 0;
}
void cur_time(void)
{
char *wday[]={"星期天","星期一","星期二","星期三","星期四","星期五","星期六"};
time_t timep;
struct tm *p;
time(&timep);
p=gmtime(&timep); /* 获取当前时间 */
printf("%d年%02d月%02d日",(1900+p->tm_year),(1+p->tm_mon),p->tm_mday);
printf("%s %02d:%02d:%02d
",wday[p->tm_wday],(p->tm_hour+8),p->tm_min,p->tm_sec);
}
-----------------------------------------------------------
gcc gmtime.c 后运行a.out结果为：
2007年12月26日星期三 11:08:34