正则表达式范围小数 0.1 - 7.0 [英] Regular expression Range with decimal 0.1 - 7.0

问题描述

我需要一个正则表达式来验证小数点和范围.总共应存在 3 个数字，包括点，并且值必须大于 0.0.这意味着有效范围是从 0.1 到 7.0.

I need a regular expression that should validate decimal point as well as range. Totally 3 number should be present including dot and the value must be greater than 0.0. That means the valid range is from 0.1 to 7.0.

我使用了以下正则表达式:^\d{1,1}(\.\d{1,2})?$

I used the following regex: ^\d{1,1}(\.\d{1,2})?$

除了范围验证外，它工作正常.我需要改变什么?

It works fine except for the range validation. What do I need to change?

推荐答案

正则表达式在验证数字范围方面是出了名的糟糕.但这是可能的.您必须将数字范围分解为这些数字的预期文本表示:

Regexes are notoriously bad at validating number ranges. But it's possible. You have to break down the number range into the expected textual representations of those numbers:

^                  # Start of string
(?:                # Either match...
 7(?:.0)?         # 7.0 (or 7)
|                  # or
 [1-6](?:.[0-9])? # 1.0-6.9 (or 1-6)
|                  # or
 0?.[1-9]         # 0.1-0.9 (or .1-.9)
)                  # End of alternation
$                  # End of string

作为单行:

^(?:7(?:.0)?|[1-6](?:.[0-9])?|0?.[1-9])$

在 Java 中:

Pattern regex = Pattern.compile("^(?:7(?:\.0)?|[1-6](?:\.[0-9])?|0?\.[1-9])$");

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