Exclude certain numbers from range of numbers using Regular expression

Question

Could some one help me with the regular expression, where we can exclude certain numbers in between from a range of numbers.

Presently, ^([1-9][0][0-9])$

Answer 1

Described in more detail in this answer, you can use the following regex with the “Negative Lookahead” command ?!:

^((?!501|504)[0-9]*)$

You can see the regex being executed & explained here: https://regex101.com/r/mL0eG4/1

/^((?!501|504)[0-9]*)$/mg

• ^ assert position at start of a line
• 1st Capturing group ((?!501|504)[0-9]*)
  • (?!501|504) Negative Lookahead - Assert that it is impossible to match the regex below
    • 1st Alternative: 501
      • 501 matches the characters 501 literally
    • 2nd Alternative: 504
      • 504 matches the characters 504 literally
  • [0-9]* match a single character present in the list below
    • Quantifier: * Between zero and unlimited times, as many times as possible, giving back as needed [greedy]
    • 0-9 a single character in the range between 0 and 9
• $ assert position at end of a line
• m modifier: multi-line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
• g modifier: global. All matches (don't return on first match)