如何使用Perl的本地时间与print来获取时间戳？

发布时间：2020-12-15 21:21:22 所属栏目：大数据来源：网络整理

导读：我使用以下语句来获取当前时间。 print "$query executed successfully at ",localtime; print "$query executed successfully at ",(localtime); print "$query executed successfully at ".(localtime); 输出 executed successfully at 355516731103960 ex

我使用以下语句来获取当前时间。

print "$query executed successfully at ",localtime;
  print "$query executed successfully at ",(localtime);
  print "$query executed successfully at ".(localtime);

输出

executed successfully at 355516731103960
 executed successfully at 355516731103960
 executed successfully at Wed Apr  7 16:55:35 2010

前两个语句不是以日期格式打印当前时间。
第三个声明只给出日期格式的正确输出。

我的理解是第一个在标量上下文中返回一个值，所以它返回数字。

然后在第二次打印中，我仅在列表上下文中使用本地时间，为什么还会输出数字输出。

解决方法

也许最重要的事情你可以学习编程在Perl，是上下文。许多内置子程序和运算符根据上下文的不同而有所不同。

print "$query executed successfully at ",localtime,"n"; # list context
print "$query executed successfully at ",(localtime),"n"; # list context
print "$query executed successfully at ". localtime,"n"; # scalar context
print "$query executed successfully at ".(localtime),"n"; # scalar context

print "$query executed successfully at ",scalar  localtime,"n"; # scalar context
print "$query executed successfully at ",scalar (localtime),"n"; # scalar context

这可以通过拆分语句来更清楚。

my $time = localtime; # scalar context
print "$query executed successfully at $timen";

my @time = localtime; # list context
print "$query executed successfully at @timen";

（编辑：李大同）

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