如何编写正则匹配5至100间可选逗号分隔的整数？

算力阿峰

2026-5-27

Solution

To match a nullable comma-separated string where every integer is between 5 and 100 (inclusive), with no trailing commas, use this regex:

^(?:(?:5|6|7|8|9|[1-9]\d|100)(?:,(?:5|6|7|8|9|[1-9]\d|100))*)?$

Breakdown of the Regex

Let's break down each component to understand how it enforces your requirements:

^ and $: Anchors to ensure we match the entire string from start to finish (no partial matches slip through).
(?: ... )?: A non-capturing group wrapping the entire valid number sequence, marked optional with ? to allow the empty string case.
(?:5|6|7|8|9|[1-9]\d|100): Matches a single valid number in the range 5-100:
- 5|6|7|8|9: Covers single-digit numbers from 5 to 9.
- [1-9]\d: Covers two-digit numbers from 10 to 99 (first digit 1-9, second digit 0-9).
- 100: Explicitly matches the three-digit number 100.
(?:,(?:5|6|7|8|9|[1-9]\d|100))*: Matches zero or more additional valid numbers preceded by a comma. The * allows multiple entries, and non-capturing groups avoid unnecessary capture of subparts.

"": The optional outer group is skipped, so it matches.
"12": Fits the two-digit number pattern [1-9]\d.
"5,100": 5 (single-digit) followed by a comma and 100 (exact match).
"5,34,55,12": All numbers fall within 5-100, separated by commas with no trailing comma.
"5,8,15,9,94": All entries are valid numbers in sequence.

"2": 2 isn't in the valid single-digit range (5-9), so no match.
"4,15": 4 is invalid, breaking the entire sequence.
"87, 3": 3 is invalid, plus the space after the comma isn't allowed (your original regex also rejects spaces; see the note below if you need to permit this).
"39,7,23,62, 1": 1 is invalid, so the string doesn't match.
"25,": Trailing comma—there's no valid number after the comma, so the sequence doesn't fit the pattern.

If you need to permit optional spaces before/after commas (e.g., "5, 100" or "5 , 100"), modify the regex to include \s* around the comma:

^(?:(?:5|6|7|8|9|[1-9]\d|100)(?:\s*,\s*(?:5|6|7|8|9|[1-9]\d|100))*)?$

This adds \s* (zero or more whitespace characters) before and after each comma, making spaces optional.

内容的提问来源于stack exchange，提问作者Mutai Mwiti