Perl date and time

In this chapter, we introduce to you how Perl language handles time and date.

The functions that handle time in Perl are as follows:

• 1. time() function: Returns from January 1, 1970 The accumulated number of seconds since

• 2. localtime() function: Get the local time zone time

• 3 , gmtime() function: Get Greenwich Mean Time

Current time and date

Let us look at localtime( ) Function that returns the current time and date without parameters.

The following 9 symbols represent different time and date parameters:

sec,     # 秒， 0 到 61
min,     # 分钟， 0 到 59
hour,    # 小时， 0 到 24
mday,    # 天， 1 到 31
mon,     # 月， 0 到 11
year,    # 年，从 1900 开始
wday,    # 星期几，0-6,0表示周日
yday,    # 一年中的第几天,0-364,365
isdst    # 如果夏令时有效，则为真

The example demonstration is as follows:

#!/usr/bin/perl
 
@months = qw( 一月 二月 三月 四月 五月 六月 七月 八月 九月 十月 十一月 十二月 );
@days = qw(星期天 星期一 星期二 星期三 星期四 星期五 星期六);

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime();
print "$mday $months[$mon] $days[$wday]\n";

The execution output result of the above example is:

12 六月 星期天

If Directly call localtime(), which returns the time of the system's current time zone setting. The example is as follows:

#!/usr/bin/perl
 
$datestring = localtime();
print "时间日期为：$datestring\n";

The execution output result of the above example is:

时间日期为：Sun Jun 12 11:27:31 2016

Greenwich Mean Time (GMT)

Functiongmtime() Similar to localtime(), but it returns standard Greenwich Time.

#!/usr/bin/perl

$local_datestring = localtime();
print "本地时间日期为：$local_datestring\n";

$gmt_datestring = gmtime();
print "GMT 时间日期为：$gmt_datestring\n";

The execution output of the above example is:

本地时间日期为：Sun Jun 12 11:32:14 2016
GMT 时间日期为：Sun Jun 12 03:32:14 2016

From the example we can see that the time in China is 8 hours different from Greenwich Mean Time.

Format date and time

We can use the 9 time elements of the localtime() function to output the format time that needs to be formulated. Formatted output uses the printf() function:

#!/usr/bin/perl
 
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime();

printf("格式化时间：HH:MM:SS\n");
printf("%02d:%02d:%02d", $hour, $min, $sec);

The above example execution output result is:

格式化时间：HH:MM:SS
11:35:23

New Epoch Time (Epoch Time)

We can use time( ) function to get the epoch time, which returns the number of seconds since January 1, 1970. The example is as follows:

#!/usr/bin/perl
 
$epoc = time();

print "从1970年1月1日起累计的秒数为：$epoc\n";

The execution output result of the above example is:

从1970年1月1日起累计的秒数为：1465702883

We can output a time format we want:

#!/usr/bin/perl

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime();
print "当期时间和日期：";
printf("%d-%d-%d %d:%d:%d",$year+1990,$mon+1,$mday,$hour,$min,$sec);

print "\n";

$epoc = time();
$epoc = $epoc - 24 * 60 * 60;   # 一天前的时间秒数
($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime($epoc);
print "昨天时间和日期：";
printf("%d-%d-%d %d:%d:%d",$year+1990,$mon+1,$mday,$hour,$min,$sec);

print "\n";

The execution output result of the above example is:

当期时间和日期：2106-6-12 11:49:28
昨天时间和日期：2106-6-11 11:49:28

POSIX function strftime()

The function strftime() can format the time into the format we want.

The following table lists some formatting symbols. The * symbol indicates that you want to rely on local time:

时间日期 - 2016-06-12 12:15:13
时间日期 - 2016-06-12 04:15:13

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#!/usr/bin/perl
use POSIX qw(strftime);

$datestring = strftime "%Y-%m-%d %H:%M:%S", localtime;
printf("时间日期 - $datestring\n");

#  GMT 格式化时间日期
$datestring = strftime "%Y-%m-%d %H:%M:%S", gmtime;
printf("时间日期 - $datestring\n");