regex - 如何匹配小于或等于100的数字？

Question

我想匹配一个小于或等于100的数字，它可以是0到100之间的任何数字，但是正则表达式不应该匹配大于100的数字，例如120、130、150、999等。

Answer 1

试试这个

\b(0*(?:[1-9][0-9]?|100))\b

说明

"
\b                # Assert position at a word boundary
(                 # Match the regular expression below and capture its match into backreference number 1
   0              # Match the character “0” literally
      *           # Between zero and unlimited times, as many times as possible, giving back as needed (greedy)
   (?:            # Match the regular expression below
                  # Match either the regular expression below (attempting the next alternative only if this one fails)
         [1-9]    # Match a single character in the range between “1” and “9”
         [0-9]    # Match a single character in the range between “0” and “9”
            ?     # Between zero and one times, as many times as possible, giving back as needed (greedy)
      |           # Or match regular expression number 2 below (the entire group fails if this one fails to match)
         100      # Match the characters “100” literally
   )
)
\b                # Assert position at a word boundary
"