string - 使用正则表达式从字符串中提取日期

Question

我有一个从字符串中提取日期部分的用例，如下所示:

Job-2023-04-14.17.14.34

我需要输出为2023-04-14。我尝试了下面的代码:

# Extract the date part from the string using a regular expression.
my $date = $string =~ /\d{4}-\d{2}-\d{2}/;

# Check if the date part is defined.
if (defined $date) {
  # Print the date part.
  print "$date\n";
} else {
  # The date part is not defined.
  print "The string does not contain a valid date.\n";
}

但是，它打印出 1。

Answer 1

使用capturing parentheses在正则表达式中，并在 $date 两边使用括号来强制列表上下文:

my ($date) = $string =~ /(\d{4}-\d{2}-\d{2})/;

输出:

2023-04-14

另请参阅:Perl Idioms Explained - @ary = $str =~ m/(stuff)/g