Re: Print the line with the largest number from standard input

In short: the intent is it matches numbers that look like -1.2, 2.347, 47., -.58 and similar. Flag /g means global, that is to say match several times on the target variable $line, not only once. Read any book or tutorial on regex. There are also many Web sites that analyse and explain regex similar to the output below.

YAPE-Regex-Explain-4.01› perl examples/explain
\-?(?:\d+\.?\d*|\.\d+)
The regular expression:

(?-imsx:\-?(?:\d+\.?\d*|\.\d+))

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  \-?                      '-' (optional (matching the most amount
                           possible))
----------------------------------------------------------------------
  (?:                      group, but do not capture:
----------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
----------------------------------------------------------------------
    \.?                      '.' (optional (matching the most amount
                             possible))
----------------------------------------------------------------------
    \d*                      digits (0-9) (0 or more times (matching
                             the most amount possible))
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    \.                       '.'
----------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
----------------------------------------------------------------------
  )                        end of grouping
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
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Re^2: Print the line with the largest number from standard input by AnomalousMonk (Archbishop) on Jul 22, 2019 at 16:22 UTC
... any book or tutorial on regex. SSSufe: In the standard Perl distribution, perlre and perlrequick are definitive and quick, respectively, and perlretut is an excellent tutorial. See also the Monastery's Tutorials section Pattern Matching, Regular Expressions, and Parsing. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l]
Re^2: Print the line with the largest number from standard input by Anonymous Monk on Jul 23, 2019 at 02:46 UTC
Thank you a lot for your help! This is very helpful!	[reply]