创建正则表达式以接受空格/空格或十进制值

Question

我想在c＃中创建正则表达式，对于具有空白/空格/ null的值或具有2个小数点的十进制值返回true。所以不接受除此之外的其他内容。

Answer 1

Although probably not the most efficient, this regular expression should do what you want:

^((\d+[\.]\d{2})|([\.]\d{2})|()|\s*)$

It requires any decimal number to have two decimal places, but it does accept either 0.99 or .99 as an example.

If you want to allow users to enter in 9 or 9.0 or 9.01 (that is, not force the user to enter in two decimal places) you can just modify the above like this:

^((\d+([\.]\d{0,2})*)|([\.]\d{0,2})|()|\s*)$

It is just setting the quantifiers to {0,2} instead of {2}, and making the existence of decimals places optional.

Answer 2

^\s*(?:[+-]?\d*\.\d{2})?\s*$

匹配一个带有两个小数位的数字，可选地用空格包围，或者只用空/空白字符串。

Answer 3

使用这个正则表达式^(\\s+)|(([+-])?\\d+[,\\.]\\d{2})|()|(null)$

Answer 4

I would suggest this pattern to handle numbers and empty string scenario.

^[-+]?\d*(\.\d{2})?|\s*$

Reagrding NULL , I have experienced that when we pass null as an input in RegEx it throws ArgumentNullException . So my recommendation is to validate NULL using != operator by matching with null :

if(str != null && RegEx.IsMatch(str,@"^[-+]?\d*(\.\d{2})?|\s*$"))
   // valid data

where:

str = string that contains data validating

Above pattern will also allow: -.00 or -0.00 as validate decimals.