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php--常用的时间处理函数
天地四方曰宇，往古来今曰宙
时间是世界的重要组成部分，不论花开花落，还是云卷云舒都有它的影子。
但它源起何处？又将去向何方？没人知道答案，也不需要答案，我们需要的只是一个相对的起点来标识时间，现今世界普遍采用公元纪年法来表示。
公元纪年法以耶稣诞生日记为公元1年（没有公元0年），中国处于汉平帝刘衎（不会读。。。）登基第二年即元始元年。
关于时间的另一个概念是unix时间戳，是从1970年1月1日开始所经过的秒数，不考虑闰秒，什么是闰秒参考这里。
下面就来说说php中时间的处理方法，以获取当前时间为例
1 <?php2 date_default_timezone_set(‘Asia/Shanghai‘);3 echo "now is ".date("Y-m-d H:i:s",time())."\n";4 echo "now is ".date("Y-m-d H:i:s",strtotime("now"))."\n";5 $date = new DateTime();6 echo "now is ".$date->format("Y-m-d H:i:s")."\n";7 ?>
时区设置
date_default_timezone_set用于设置时区，优先级别高于php.ini中设置的date.timezone属性，可设置的时区列表见这里，与之对应的是date_default_timezone_get获取由set函数设置的时区。
1 <?php2 date_default_timezone_set(‘Asia/Shanghai‘);3 $date_set = date_default_timezone_get();4 //如果与配置文件中的时区设置相同则设置为美国时区5 if($date_set == ini_get("date.timezone")){6 date_default_timezone_set(‘America/Los_Angeles‘);7 }8 echo date("Y-m-d H:i:s")."\n";9 ?>
获取UNIX时间戳
常用的方法有三种：time(),microtime(),strotime("now")
1 <?php2 error_reporting(E_ALL ^E_STRICT);3 echo "time is ".time()."\n";4 echo "strotime is ".strtotime("now")."\n";5 echo "mktime is ".mktime()."\n";6 echo "microtime is ".microtime()."\n";7 //参数设置为true返回浮点数表示的时间戳8 echo "in float microtime is ".microtime(true)."\n";9 ?>
mktime
mktime函数的参数全是关键字参数，关键字参数大家懂的可以从右到左省略，格式为时，分，秒，月，日，年
1 <?php 2 3 //年默认2014 4 echo "mktime(10,10,10,10,12) is ".date("Y-m-d H:i:s",mktime(10,10,10,10,12))."\n"; 5 6 //这种写法会将2014当作月数，年还是默认的2014年 7 echo "mktime(10,10,10,10,2014) is ".date("Y-m-d H:i:s",mktime(10,10,10,10,2014))."\n"; 8 9 echo "mktime(10,10,10,10,32,2014) is ".date("Y-m-d H:i:s",mktime(10,10,10,10,32,2014))."\n";10 ?>
出现了一些很奇妙的事情，2014年2014月变成了2020年4月，2014年10月32号变成了11月1号，看，mktime自动计算了相差部分。乍看之下感觉很神奇，细想下来又在情理之中，毕竟日期的相互转换是通过unix时间戳进行的，我们可以通过mktime的实现源码管中窥豹一下。
该函数源码位于ext/date/php_date.c 在1500行实现，篇幅所限只贴部分代码，兴趣的朋友可以下下来自己看，地址在这里.
1 PHPAPI void php_mktime(INTERNAL_FUNCTION_PARAMETERS, int gmt) 2 { 3 zend_long hou = 0, min = 0, sec = 0, mon = 0, day = 0, yea = 0, dst = -1; 4 timelib_time *now; 5 timelib_tzinfo *tzi = NULL; 6 zend_long ts, adjust_seconds = 0; 7 int error; 8 9 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|lllllll", &hou, &min, &sec, &mon, &day, &yea, &dst) == FAILURE) {10 RETURN_FALSE;11 }12 /* Initialize structure with current time */13 now = timelib_time_ctor();14 if (gmt) {15 timelib_unixtime2gmt(now, (timelib_sll) time(NULL));16 } else {17 tzi = get_timezone_info(TSRMLS_C);18 now->tz_info = tzi;19 now->zone_type = TIMELIB_ZONETYPE_ID;20 timelib_unixtime2local(now, (timelib_sll) time(NULL));21 }22 /* Fill in the new data */23 switch (ZEND_NUM_ARGS()) {24 case 7:25 /* break intentionally missing */26 case 6:27 if (yea >= 0 && yea < 70) {28 yea += 2000;29 } else if (yea >= 70 && yea <= 100) {30 yea += 1900;31 }32 now->y = yea;33 /* break intentionally missing again */34 case 5:35 now->d = day;36 /* break missing intentionally here too */37 case 4:38 now->m = mon;39 /* and here */40 case 3:41 now->s = sec;42 /* yup, this break isn‘t here on purpose too */43 case 2:44 now->i = min;45 /* last intentionally missing break */46 case 1:47 now->h = hou;48 break;49 default:50 php_error_docref(NULL TSRMLS_CC, E_STRICT, "You should be using the time() function instead");51 }52 /* Update the timestamp */53 if (gmt) {54 timelib_update_ts(now, NULL);55 } else {56 timelib_update_ts(now, tzi);57 }58 /* Support for the deprecated is_dst parameter */59 if (dst != -1) {60 php_error_docref(NULL TSRMLS_CC, E_DEPRECATED, "The is_dst parameter is deprecated");61 if (gmt) {62 /* GMT never uses DST */63 if (dst == 1) {64 adjust_seconds = -3600;65 }66 } else {67 /* Figure out is_dst for current TS */68 timelib_time_offset *tmp_offset;69 tmp_offset = timelib_get_time_zone_info(now->sse, tzi);70 if (dst == 1 && tmp_offset->is_dst == 0) {71 adjust_seconds = -3600;72 }73 if (dst == 0 && tmp_offset->is_dst == 1) {74 adjust_seconds = +3600;75 }76 timelib_time_offset_dtor(tmp_offset);77 }78 }79 /* Clean up and return */80 ts = timelib_date_to_int(now, &error);81 ts += adjust_seconds;82 timelib_time_dtor(now);83 84 if (error) {85 RETURN_FALSE;86 } else {87 RETURN_LONG(ts);88 }89 }
阅读这段代码需知道一个重要的结构体timelib_time，在ext/date/lib/timelib_structs.h中声明
typedef struct timelib_time { timelib_sll y, m, d; /* Year, Month, Day */ timelib_sll h, i, s; /* Hour, mInute, Second */ double f; /* Fraction */ int z; /* GMT offset in minutes */ char *tz_abbr; /* Timezone abbreviation (display only) */ timelib_tzinfo *tz_info; /* Timezone structure */ signed int dst; /* Flag if we were parsing a DST zone */ timelib_rel_time relative; timelib_sll sse; /* Seconds since epoch */ unsigned int have_time, have_date, have_zone, have_relative, have_weeknr_day; unsigned int sse_uptodate; /* !0 if the sse member is up to date with the date/time members */ unsigned int tim_uptodate; /* !0 if the date/time members are up to date with the sse member */ unsigned int is_localtime; /* 1 if the current struct represents localtime, 0 if it is in GMT */ unsigned int zone_type; /* 1 time offset, * 3 TimeZone identifier, * 2 TimeZone abbreviation */} timelib_time;
现在来看看mktime,56行的timelib_update_ts函数位于ext/date/lib/tm2unixtime.c文件中，其作用是根据now中的日期信息计算相应的秒数并存入now->sse，来看看
1 void timelib_update_ts(timelib_time* time, timelib_tzinfo* tzi) 2 { 3 timelib_sll res = 0; 4 5 do_adjust_special_early(time); 6 do_adjust_relative(time); 7 do_adjust_special(time); 8 res += do_years(time->y); 9 res += do_months(time->m, time->y);10 res += do_days(time->d);11 res += do_time(time->h, time->i, time->s);12 time->sse = res;13 14 res += do_adjust_timezone(time, tzi);15 time->sse = res;16 17 time->sse_uptodate = 1;18 time->have_relative = time->relative.have_weekday_relative = time->relative.have_special_relative = 0;19 }
8-11行计算相应时间类型的秒数，到这里已可了解mktime自动增减日期的原理，让我们看看do_days是如何实现的。day-1应该不难理解，mktime前面需要传入小时分钟等参数，在处理具体的某一天时默认为当天的0点0分0秒，所以要比实际的天数少一天。do_months,do_years等机制都相同，不再细述。
static timelib_sll do_days(timelib_ull day){ return ((day - 1) * SECS_PER_DAY);}
当日期处理完成，我们回到php_date.c，在80行处通过timelib_date_to_int函数将now->sse返回，该函数位于ext/date/lib/timelib.c，具体的代码就不贴了。
strtotime
聊完了mktime，再来看看strtotime，同样先来几个例子
<?php echo "strtotime(‘+1 day‘,strtotime(‘2014/10/19‘)) is ".date("Y-m-d",strtotime("+1 day",strtotime("2014/10/19")))."\n"; echo "strtotime(‘-30 day‘) is ".date("Y-m-d",strtotime("-30 day"))."\n"; echo "strtotime(‘+1 week‘) is ".date("Y-m-d",strtotime("+1 week"))."\n"; echo "strtotime(‘last Monday) is ".date("Y-m-d",strtotime("last Monday"))."\n";?>
strtotime相较mktime要复杂很多，在于其对英文文本的解析过程，这里用到了词法解析工具re2c，原始文件位于ext/date/lib/parse_date.re,同目录下还有个parse_date.c是编译后的文件,parse_date.c太大，我们分析parse_date.re就可以了，以strtotime("+1 day")为例，下面是php_date.c中的实现代码
1 PHP_FUNCTION(strtotime) 2 { 3 char *times, *initial_ts; 4 size_t time_len; 5 int error1, error2; 6 struct timelib_error_container *error; 7 zend_long preset_ts = 0, ts; 8 9 timelib_time *t, *now;10 timelib_tzinfo *tzi;11 12 tzi = get_timezone_info(TSRMLS_C);13 14 if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC, "sl", ×, &time_len, &preset_ts) != FAILURE) {15 /* We have an initial timestamp */16 now = timelib_time_ctor();17 18 initial_ts = emalloc(25);19 snprintf(initial_ts, 24, "@" ZEND_LONG_FMT " UTC", preset_ts);20 t = timelib_strtotime(initial_ts, strlen(initial_ts), NULL, DATE_TIMEZONEDB, php_date_parse_tzfile_wrapper); /* we ignore the error here, as this should never fail */21 timelib_update_ts(t, tzi);22 now->tz_info = tzi;23 now->zone_type = TIMELIB_ZONETYPE_ID;24 timelib_unixtime2local(now, t->sse);25 timelib_time_dtor(t);26 efree(initial_ts);27 } else if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", ×, &time_len, &preset_ts) != FAILURE) {28 /* We have no initial timestamp */29 now = timelib_time_ctor();30 now->tz_info = tzi;31 now->zone_type = TIMELIB_ZONETYPE_ID;32 timelib_unixtime2local(now, (timelib_sll) time(NULL));33 } else {34 RETURN_FALSE;35 }36 37 if (!time_len) {38 timelib_time_dtor(now); 39 RETURN_FALSE;40 }41 42 t = timelib_strtotime(times, time_len, &error, DATE_TIMEZONEDB, php_date_parse_tzfile_wrapper);43 error1 = error->error_count;44 timelib_error_container_dtor(error);45 timelib_fill_holes(t, now, TIMELIB_NO_CLONE);46 timelib_update_ts(t, tzi);47 ts = timelib_date_to_int(t, &error2);48 49 timelib_time_dtor(now);50 timelib_time_dtor(t);51 52 if (error1 || error2) {53 RETURN_FALSE;54 } else {55 RETURN_LONG(ts);56 }57 }
if用来解析参数，分为有第二个参数和没有第二个参数的情况，这里略过不提，主要关注timelib_strtotime函数，它在parse_date.re中定义，返回解析后的timelib_time结构体。而timelib_strtotime又会调用parse_date.re中的scan方法来解析字符串，这里有几个重要的正则表达式
reltextnumber = ‘first‘|‘second‘|‘third‘|‘fourth‘|‘fifth‘|‘sixth‘|‘seventh‘|‘eight‘|‘eighth‘|‘ninth‘|‘tenth‘|‘eleventh‘|‘twelfth‘;reltexttext = ‘next‘|‘last‘|‘previous‘|‘this‘;reltextunit = ((‘sec‘|‘second‘|‘min‘|‘minute‘|‘hour‘|‘day‘|‘fortnight‘|‘forthnight‘|‘month‘|‘year‘) ‘s‘?) | ‘weeks‘ | daytext;relnumber = ([+-]*[ \t]*[0-9]+);relative = relnumber space? (reltextunit | ‘week‘ );relativetext = (reltextnumber|reltexttext) space reltextunit;relativetextweek = reltexttext space ‘week‘;
"+1 day"会被解析为relative,并进行relative的相关操作
relative { timelib_ull i; DEBUG_OUTPUT("relative"); TIMELIB_INIT; TIMELIB_HAVE_RELATIVE(); while(*ptr) { i = timelib_get_unsigned_nr((char **) &ptr, 24); timelib_eat_spaces((char **) &ptr); timelib_set_relative((char **) &ptr, i, 1, s); } TIMELIB_DEINIT; return TIMELIB_RELATIVE; }
timelib_get_unsigned_nr 用来判断是"+"还是"-"，参数24用来指定最大的字符串长度，然后调用timelib_get_nr获取后面的具体数字，最后调用timelib_set_relative设置timelib_time 结构体中relative.d=1。
static timelib_ull timelib_get_unsigned_nr(char **ptr, int max_length){ timelib_ull dir = 1; while (((**ptr < ‘0‘) || (**ptr > ‘9‘)) && (**ptr != ‘+‘) && (**ptr != ‘-‘)) { if (**ptr == ‘\0‘) { return TIMELIB_UNSET; } ++*ptr; } while (**ptr == ‘+‘ || **ptr == ‘-‘) { if (**ptr == ‘-‘) { dir *= -1; } ++*ptr; } return dir * timelib_get_nr(ptr, max_length);}
1 static void timelib_set_relative(char **ptr, timelib_sll amount, int behavior, Scanner *s) 2 { 3 const timelib_relunit* relunit; 4 5 if (!(relunit = timelib_lookup_relunit(ptr))) { 6 return; 7 } 8 9 switch (relunit->unit) {10 case TIMELIB_SECOND: s->time->relative.s += amount * relunit->multiplier; break;11 case TIMELIB_MINUTE: s->time->relative.i += amount * relunit->multiplier; break;12 case TIMELIB_HOUR: s->time->relative.h += amount * relunit->multiplier; break;13 case TIMELIB_DAY: s->time->relative.d += amount * relunit->multiplier; break;14 case TIMELIB_MONTH: s->time->relative.m += amount * relunit->multiplier; break;15 case TIMELIB_YEAR: s->time->relative.y += amount * relunit->multiplier; break;16 17 case TIMELIB_WEEKDAY:18 TIMELIB_HAVE_WEEKDAY_RELATIVE();19 TIMELIB_UNHAVE_TIME();20 s->time->relative.d += (amount > 0 ? amount - 1 : amount) * 7;21 s->time->relative.weekday = relunit->multiplier;22 s->time->relative.weekday_behavior = behavior;23 break;24 25 case TIMELIB_SPECIAL:26 TIMELIB_HAVE_SPECIAL_RELATIVE();27 TIMELIB_UNHAVE_TIME();28 s->time->relative.special.type = relunit->multiplier;29 s->time->relative.special.amount = amount;30 }31 }
随后就和mktime一样调用相关处理函数转换为时间戳，有一点需要注意，timelib_set_relative的实现方式是直接在日期或月份上操作，下面这样的代码会出现问题
echo date("Y-m-d",strtotime("-1 month",strtotime("2014/03/31")))."\n";
输出结果为2014-03-03，按照上述流程，2014/03/31会转为2014/02/31处理，等价于mktime(00,00,00,2,31,2014),mktime的处理方式上文已经说过了:P
写一些常用的方法
知道了原理，用起来就很方便了。下面是使用频率较高的时间处理方法，例如获取前几周，前几天，取得本周第一天和最后一天的时间等等，不定期更新,github地址。
1 <?php 2 3 /** 4 * process date 5 * @author huntstack 6 * @time 2014-10-18 7 */ 8 class Process_Date{ 9 10 private $date; 11 private $M,$D,$Y; 12 13 /** 14 * set the date for next operator 15 * @parameter date:time string or timestamp 16 */ 17 function __construct($date=""){ 18 if($date == "" || empty($date)){ 19 $this->date = strtotime("now"); 20 }else if(gettype($date) == "string"){ 21 $this->date = strtotime($date); 22 }else if(gettype($date) == "integer"){ 23 $this->date = $date; 24 }else{ 25 throw new Exception("paramter must be timestamp or date string or empty for current time"); 26 } 27 $this->set_varibales(); 28 } 29 30 public function set_date($date){ 31 $this->date = strtotime($date); 32 $this->set_varibales(); 33 } 34 35 private function set_varibales(){ 36 $this->M = date("m",$this->date); 37 $this->D = date("d",$this->date); 38 $this->Y = date("Y",$this->date); 39 } 40 41 /** 42 * get the specified weeks 43 * @parameter $i:numbers of week 44 * @parameter $flag:0->last,1->next 45 */ 46 public function get_week($i=0,$flag=1){ 47 if($flag == 0) return date("YW",strtotime("-$i week",$this->date)); 48 else if($flag == 1) return date("YW",strtotime("+$i week",$this->date)); 49 } 50 51 /** 52 * get the specified months 53 * @parameter $i:numbers of month 54 * @parameter $flag:0->last,1->next 55 */ 56 public function get_month($i=0,$flag=1){ 57 if($flag == 0) return date("Y-m",mktime(0,0,0, $this->M-$i, 1, $this->Y)); 58 else if($flag == 1) return date("Y-m",mktime(0,0,0, $this->M+$i, 1, $this->Y)); 59 } 60 61 /** 62 * get the specified days 63 * @parameter $i:numbers of day 64 * @parameter $flag:0->last,1->next 65 */ 66 public function get_day($i=0,$flag=1){ 67 if($flag == 0) return date("Y-m-d",mktime(0,0,0, $this->M, $this->D-$i, $this->Y)); 68 else if($flag == 1) return date("Y-m-d",mktime(0,0,0, $this->M, $this->D+$i, $this->Y)); 69 } 70 71 /** 72 * get the last $count days 73 * @parameter count:number 74 */ 75 public function get_last_days($count){ 76 $return = array(); 77 for($i=1;$i<=$count;$i++){ 78 array_push($return, $this->get_day($i,0)); 79 } 80 return $return; 81 } 82 83 /** 84 * get the next $count days 85 * @parameter count:number 86 */ 87 public function get_next_days($count){ 88 $return = array(); 89 for($i=1;$i<=$count;$i++){ 90 array_push($return, $this->get_day($i,1)); 91 } 92 return $return; 93 } 94 95 /** 96 * get the last $count weeks 97 * @parameter count:number 98 */ 99 public function get_last_weeks($count){100 $return = array();101 for($i=1;$i<=$count;$i++){102 array_push($return, $this->get_week($i,0));103 }104 return $return;105 }106 107 /**108 * get the next $count weeks 109 * @parameter count:number110 */111 public function get_next_weeks($count){112 $return = array();113 for($i=1;$i<=$count;$i++){114 array_push($return, $this->get_week($i,1));115 }116 return $return;117 }118 119 /**120 * get the last $count months121 * @parameter count:number122 */123 public function get_last_month($count){124 $return = array();125 for($i=1;$i<=$count;$i++){126 array_push($return, $this->get_month($i,0));127 }128 return $return;129 }130 131 /**132 * get the next $count months133 * @parameter count:number134 */135 public function get_next_month($count){136 $return = array();137 for($i=1;$i<=$count;$i++){138 array_push($return, $this->get_month($i,1));139 }140 return $return;141 }142 143 /**144 * get the first day and the last day of a week145 */146 public function get_week_begin_end(){147 $return["begin"] = mktime(0,0,0, $this->M, $this->D-date("w",$this->date)+1, $this->Y);148 $return["end"] = mktime(23,59,59, $this->M, $this->D-date("w",$this->date)+7, $this->Y);149 return $return;150 }151 152 /**153 * get the first day and the last day of a month154 */155 public function get_month_begin_end(){156 $return["begin"] = strtotime("first day of",$this->date);157 $return["end"] = strtotime("last day of",$this->date);158 return $return;159 }160 }161 ?>
参考资料：
1.http://php.net/manual/zh/book.datetime.php
2.http://www.phppan.com/2011/06/php-strtotime/
php--常用的时间处理函数
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