需要这个正则表达式来检查3位小数？

Question

我有：

^-?[0-9]\d*(\.\d+)?$

但需要它只允许最多3位小数。所以允许的值是：

+10.123

-10.123

10.123

10

+10

-10

10.1

10.12

不允许：

10.1234

10.123%

建议/建议的表达模式赞赏。

提前致谢。

Answer 1

除了指定无限重复的*和+元字符外，正则表达式还允许您对{a,b}的匹配数量设置特定限制构造。此处，a是所需的最低匹配数，b是最大匹配数。 a和b都是包含。

由于您需要匹配至少一个，最多三个数字，因此您需要将\d+替换为\d{1,3}：

^[+-]?[0-9]\d*(\.\d{1,3})?$

优化：掌握有效的正则表达式，您可以将[0-9]替换为另一个\d进行优化，并使用“{1}}”将其“折叠”为\d* \d+：

^[+-]?\d+(\.\d{1,3})?$

Answer 2

^[+-]{0,1}\d*?(\.{0,1}\d{0,3})?$应该有效

请参阅https://regex101.com/r/P6DBrW/1/了解正则表达式的解释

Answer 3

 ^[+-]?\d+(\.\d{1,3})?$

说明：

请在此处查看：https://www.debuggex.com/r/BbCBL5pQWLxsD4a6

^ asserts position at start of a line
   Match a single character present in the list below [+-]?
     ? Quantifier — Matches between zero and one times, as many times as possible, 
                    giving back as needed (greedy)
     +- matches a single character in the list +- (case sensitive)
   \d+ matches a digit (equal to [0-9])
      + Quantifier — Matches between one and unlimited times, as many times as possible, 
                     giving back as needed (greedy)
   1st Capturing Group (\.\d{1,3})?
     ? Quantifier — Matches between zero and one times, as many times as possible, 
                    giving back as needed (greedy)
     \. matches the character . literally (case sensitive)
     \d{1,3} matches a digit (equal to [0-9])
     {1,3} Quantifier — Matches between 1 and 3 times, as many times as possible, 
                        giving back as needed (greedy)
   $ asserts position at the end of a line

解释来自：{https://regex101.com/]

Answer 4

^(?!0\d)\d*         
(\.\d{1,4})?$