linux時(shí)間編程

1、1、Linux下常用時(shí)間類型Linux下常用時(shí)間類型有四種：time_t、struct tm、struct timeval、struct timespec1.1 time_t時(shí)間類型time_t類型在time.h中定義：cpp view plaincopyprint?1. #ifndef _TIME_T 2. #define _TIME_T 3. typedef long time_t; 4. #endif #ifndef _TIME_T#define _TIME_Ttypedef long time_t;#endif可見，time_t實(shí)際是一個(gè)長整型。其值表示為從UTC(coordinate

2、d universal time)時(shí)間1970年1月1日00時(shí)00分00秒(也稱為Linux系統(tǒng)的Epoch時(shí)間)到當(dāng)前時(shí)刻的秒數(shù)。由于time_t類型長度的限制，它所表示的時(shí)間不能晚于2038年1月19日03時(shí)14分07秒(UTC)。為了能夠表示更久遠(yuǎn)的時(shí)間，可用64位或更長的整形數(shù)來保存日歷時(shí)間，這里不作詳述。使用time()函數(shù)獲取當(dāng)前時(shí)間的time_t值，使用ctime()函數(shù)將time_t轉(zhuǎn)為當(dāng)?shù)貢r(shí)間字符串。備注：UTC時(shí)間有時(shí)也稱為GMT時(shí)間，其實(shí)UTC和GMT兩者幾乎是同一概念。它們都是指格林尼治標(biāo)準(zhǔn)時(shí)間，只不過UTC的稱呼更為正式一點(diǎn)。兩者區(qū)別在于前者是天文上的概念，而后者是基

3、于一個(gè)原子鐘。1.2 struct tm時(shí)間類型tm結(jié)構(gòu)在time.h中定義：cpp view plaincopyprint?1. #ifndef _TM_DEFINED 2. struct tm 3. int tm_sec; /*秒 - 取值區(qū)間為0, 59*/ 4. int tm_min; /*分 - 取值區(qū)間為0, 59*/ 5. int tm_hour; /*時(shí) - 取值區(qū)間為0, 23*/ 6. int tm_mday; /*日 - 取值區(qū)間為1, 31*/ 7. int tm_mon; /*月份 - 取值區(qū)間為0, 11*/ 8. int tm_year; /*年份 - 其值為19

4、00年至今年數(shù)*/ 9. int tm_wday; /*星期 - 取值區(qū)間0, 6，0代表星期天，1代表星期1，以此類推*/ 10. int tm_yday; /*從每年的1月1日開始的天數(shù)-取值區(qū)間為0, 365，0代表1月1日*/ 11. int tm_isdst; /*夏令時(shí)標(biāo)識符，使用夏令時(shí)，tm_isdst為正，不使用夏令時(shí)，tm_isdst為0，不了解情況時(shí)，tm_isdst為負(fù)*/ 12. ; 13. #define _TM_DEFINED 14. #endif #ifndef _TM_DEFINEDstruct tm int tm_sec; /*秒 - 取值區(qū)間為0, 59*/

5、 int tm_min; /*分 - 取值區(qū)間為0, 59*/ int tm_hour; /*時(shí) - 取值區(qū)間為0, 23*/ int tm_mday; /*日 - 取值區(qū)間為1, 31*/ int tm_mon; /*月份 - 取值區(qū)間為0, 11*/ int tm_year; /*年份 - 其值為1900年至今年數(shù)*/ int tm_wday; /*星期 - 取值區(qū)間0, 6，0代表星期天，1代表星期1，以此類推*/ int tm_yday; /*從每年的1月1日開始的天數(shù)-取值區(qū)間為0, 365，0代表1月1日*/ int tm_isdst; /*夏令時(shí)標(biāo)識符，使用夏令時(shí)，tm_isds

6、t為正，不使用夏令時(shí)，tm_isdst為0，不了解情況時(shí)，tm_isdst為負(fù)*/;#define _TM_DEFINED#endifANSI C標(biāo)準(zhǔn)稱使用tm結(jié)構(gòu)的這種時(shí)間表示為分解時(shí)間(broken-down time)。使用gmtime( )和localtime( )可將time_t時(shí)間類型轉(zhuǎn)換為tm結(jié)構(gòu)體；使用mktime( )將tm結(jié)構(gòu)體轉(zhuǎn)換為time_t時(shí)間類型；使用asctime( )將struct tm轉(zhuǎn)換為字符串形式。1.3 struct timeval時(shí)間類型timeval結(jié)構(gòu)體在time.h中定義：cpp view plaincopyprint?1. Struct tmi

7、eval 2. time_t tv_sec; /*秒s*/ 3. suseconds_t tv_usec; /*微秒us*/ 4. ; Struct tmieval time_t tv_sec; /*秒s*/ suseconds_t tv_usec; /*微秒us*/;設(shè)置時(shí)間函數(shù)settimeofday( )與獲取時(shí)間函數(shù)gettimeofday( )均使用該事件類型作為傳參。1.4 struct timespec時(shí)間類型timespec結(jié)構(gòu)體在time.h定義：cpp view plaincopyprint?1. struct timespec 2. time_t tv_sec; /*秒s

8、*/ 3. long tv_nsec; /*納秒ns*/ 4. ; struct timespec time_t tv_sec; /*秒s*/ long tv_nsec; /*納秒ns*/;2、Linux下常用時(shí)間函數(shù)Linux下常用時(shí)間函數(shù)有：time( )、ctime( )、gmtime( )、localtime( )、mktime( )、asctime( )、difftime( )、gettimeofday( )、settimeofday( )2.1 time( )函數(shù)頭文件：#include <time.h>函數(shù)定義：time_t time(time_t *timer)功能

9、描述：該函數(shù)返回從1970年1月1日00時(shí)00分00秒至今所經(jīng)過的秒數(shù)。如果time_t *timer非空指針，函數(shù)也會將返回值存到timer指針指向的內(nèi)存。返回值：成功則返回秒數(shù)，失敗則返回(time_t)-1)值，錯誤原因存于errno中。例：cpp view plaincopyprint?1. time_t seconds; 2. seconds = time(time_t *)NULL); time_t seconds;seconds = time(time_t *)NULL);2.2 ctime( )函數(shù)頭文件：#include <time.h>函數(shù)定義：char *ct

10、ime(const time_t *timep);功能描述：ctime( )將參數(shù)timep指向的time_t時(shí)間信息轉(zhuǎn)換成實(shí)際所使用的時(shí)間日期表示方法，并以字符串形式返回。字符串格式為："Wed Jun 20 21:00:00 2012n"。例：cpp view plaincopyprint?1. time_t timep; 2. tmep = time(NULL); 3. printf("%sn", ctime(&timep); time_t timep;tmep = time(NULL);printf("%sn", ct

11、ime(&timep);2.3 gmtime( )函數(shù)頭文件：#include <time.h>函數(shù)定義：struct tm *gmtime(const time_t *timep)功能描述：gmtime( )將參數(shù)timep指向的time_t時(shí)間信息轉(zhuǎn)換成以tm結(jié)構(gòu)體表示的GMT時(shí)間信息，并以struct tm*指針返回。GMT：GMT是中央時(shí)區(qū),北京在東8區(qū),相差8個(gè)小時(shí)，所以北京時(shí)間=GMT時(shí)間+8小時(shí)。例：cpp view plaincopyprint?1. int main(void) 2. 3. char *wday = "Sun", &qu

12、ot;Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 4. time_t timep; 5. struct tm *p_tm; 6. timep = time(NULL); 7. p_tm = gmtime(&timep); /*獲取GMT時(shí)間*/ 8. printf("%d-%d-%d ", (p_tm->tm_year+1900), (p_tm->mon+1), p_tm->tm_mday); 9. pr

13、intf("%s %d:%d:%dn", wdayp_tm->tm_wday, p_tm->tm_hour, p_tm->tm_min, p_tm->tm_sec); 10. int main(void) char *wday = "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" time_t timep; struct tm *p_tm; timep = time(

14、NULL); p_tm = gmtime(&timep); /*獲取GMT時(shí)間*/ printf("%d-%d-%d ", (p_tm->tm_year+1900), (p_tm->mon+1), p_tm->tm_mday); printf("%s %d:%d:%dn", wdayp_tm->tm_wday, p_tm->tm_hour, p_tm->tm_min, p_tm->tm_sec);2.4 localtime( )函數(shù)頭文件：#include <time.h>函數(shù)定義：struc

15、t tm *localtime(const time_t *timep);功能描述：localtime( )將參數(shù)timep指向的time_t時(shí)間信息轉(zhuǎn)換成以tm結(jié)構(gòu)體表示的本地時(shí)區(qū)時(shí)間(如北京時(shí)間= GMT+小時(shí))。例：cpp view plaincopyprint?1. int main(void) 2. 3. char *wday = "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 4. time_t

16、timep; 5. struct tm *p_tm; 6. timep = time(NULL); 7. p_tm = localtime(&timep); /*獲取本地時(shí)區(qū)時(shí)間*/ 8. printf("%d-%d-%d ", (p_tm->tm_year+1900), (p_tm->mon+1), p_tm->tm_mday); 9. printf("%s %d:%d:%dn", wdayp_tm->tm_wday, p_tm->tm_hour, p_tm->tm_min, p_tm->tm_sec)

17、; 10. return 0; 11. int main(void) char *wday = "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" time_t timep; struct tm *p_tm; timep = time(NULL); p_tm = localtime(&timep); /*獲取本地時(shí)區(qū)時(shí)間*/ printf("%d-%d-%d ", (p_tm->

18、tm_year+1900), (p_tm->mon+1), p_tm->tm_mday); printf("%s %d:%d:%dn", wdayp_tm->tm_wday, p_tm->tm_hour, p_tm->tm_min, p_tm->tm_sec); return 0;2.5 mktime( )函數(shù)頭文件：#include <time.h>函數(shù)定義：time_t mktime(struct tm *p_tm);功能描述：mktime( )將參數(shù)p_tm指向的tm結(jié)構(gòu)體數(shù)據(jù)轉(zhuǎn)換成從1970年1月1日00時(shí)00分00秒

19、至今的GMT時(shí)間經(jīng)過的秒數(shù)。例：cpp view plaincopyprint?1. int main(void) 2. 3. time_t timep: 4. struct tm *p_tm; 5. timep = time(NULL); 6. pintf("time( ):%dn", timep); 7. p_tm = local(&timep); 8. timep = mktime(p_tm); 9. printf("time( )->localtime( )->mktime( ):%dn", timep); 10. retur

20、n 0; 11. int main(void) time_t timep: struct tm *p_tm; timep = time(NULL); pintf("time( ):%dn", timep); p_tm = local(&timep); timep = mktime(p_tm); printf("time( )->localtime( )->mktime( ):%dn", timep); return 0;2.6 asctime( )函數(shù)頭文件：#include <time.h>函數(shù)定義：char *asct

21、ime(const struct tm *p_tm);功能描述：asctime( )將參數(shù)p_tm指向的tm結(jié)構(gòu)體數(shù)據(jù)轉(zhuǎn)換成實(shí)際使用的時(shí)間日期表示方法，并以字符串形式返回(與ctime函數(shù)相同)。字符串格式為："Wed Jun 20 21:00:00 2012n"。例：cpp view plaincopyprint?1. int main(void) 2. 3. time_t timep; 4. timep = time(NULL); 5. printf("%sn", asctime(gmtime(&timep); 6. return 0; 7.

22、 int main(void) time_t timep; timep = time(NULL); printf("%sn", asctime(gmtime(&timep); return 0;2.7 difftime( )函數(shù)頭文件：#include <time.h>函數(shù)定義：double difftime(time_t timep1, time_t timep2);功能描述：difftime( )比較參數(shù)timep1和timep2時(shí)間是否相同，并返回之間相差秒數(shù)。例：cpp view plaincopyprint?1. int main(void)

23、2. 3. time_t timep1, timep2; 4. timep1 = time(NULL); 5. sleep(2); 6. timep2 = time(NULL); 7. printf("the difference is %f secondsn", difftime(timep1, timep2); 8. return 0; 9. int main(void) time_t timep1, timep2; timep1 = time(NULL); sleep(2); timep2 = time(NULL); printf("the differen

24、ce is %f secondsn", difftime(timep1, timep2); return 0;2.8 gettimeofday( )函數(shù)頭文件：#include <sys/time.h>#include <unistd.h>函數(shù)定義：int gettimeofday(struct timeval *tv, struct timezone *tz);功能描述：gettimeofday( )把目前的時(shí)間信息存入tv指向的結(jié)構(gòu)體，當(dāng)?shù)貢r(shí)區(qū)信息則放到tz指向的結(jié)構(gòu)體。struct timezone原型：cpp view plaincopyprint?1

25、. struct timezone 2. int tz_minuteswest; /*miniutes west of Greenwich*/ 3. int tz_dsttime; /*type of DST correction*/ 4. ; struct timezone int tz_minuteswest; /*miniutes west of Greenwich*/ int tz_dsttime; /*type of DST correction*/;例：cpp view plaincopyprint?1. struct timeval tv; 2. struct timeval t

26、z; 3. gettimeofday(&tv, &tz); struct timeval tv;struct timeval tz;gettimeofday(&tv, &tz);附：使用time函數(shù)族獲取時(shí)間并輸出指定格式字符串例子（strftime( )函數(shù)）：cpp view plaincopyprint?1. int main(void) 2. 3. char strtime20 = 0; 4. time_t timep; 5. struct tm *p_tm; 6. timep = time(NULL); 7. p_tm = localtime(&

27、;timep); 8. strftime(strtime, sizeof(strtime), "%Y-%m-%d %H:%M:%S", p_tm); 9. return 0; 10. int main(void) char strtime20 = 0; time_t timep; struct tm *p_tm; timep = time(NULL); p_tm = localtime(&timep); strftime(strtime, sizeof(strtime), "%Y-%m-%d %H:%M:%S", p_tm); return 0;2.9 settimeofday( )函數(shù)頭文件：#include <sys/time.h&