正则表达式C＃断言字符串是分数

Question

所有，

我需要2个正则表达式，它可以在.NET来检测用户是否在一小部分类型：

1. 只有分数值没有任何整部分（不想检查1 1/4，3 1/2等） ONLY：1/2，3/4，8/3等。分子分母可以是浮点数或整数。

2. ALL有效馏分，例如1/3，2/3，1 1/4等

感谢。

Answer 1

对于第一

对于在##/##，其中分子或分母可以是任何长度形式的任何部分，你可以只使用：

\d+(\.\d+)?/\d+(\.\d+)? 

抓住尽可能多的数字作为您可以立即在字面斜杠前后，只要至少有一个或多个这些数字。如果有一个小数点，它也必须跟着一个或多个数字，但整个组是可选的，只能出现一次。

对于第二

假设它必须是一小部分，因此整体人数就喜欢1起不到作用，只要坚持正面

\d*\s* 

抓住以下一些数字并在其余部分之前留出空白。

Answer 2

试试这个：

/// <summary> 
/// A regular expression to match fractional expression such as '1 2/3'. 
/// It's up to the user to validate that the expression makes sense. In this context, the fractional portion 
/// must be less than 1 (e.g., '2 3/2' does not make sense), and the denominator must be non-zero. 
/// </summary> 
static Regex FractionalNumberPattern = new Regex(@" 
    ^     # anchor the start of the match at the beginning of the string, then... 
    (?<integer>-?\d+)  # match the integer portion of the expression, an optionally signed integer, then... 
    \s+     # match one or more whitespace characters, then... 
    (?<numerator>\d+)  # match the numerator, an unsigned decimal integer 
          # consisting of one or more decimal digits), then... 
    /     # match the solidus (fraction separator, vinculum) that separates numerator from denominator 
    (?<denominator>\d+) # match the denominator, an unsigned decimal integer 
          # consisting of one or more decimal digits), then... 
    $      # anchor the end of the match at the end of the string 
    ", RegexOptions.IgnorePatternWhitespace 
    ); 

/// <summary> 
/// A regular expression to match a fraction (rational number) in its usual format. 
/// The user is responsible for checking that the fraction makes sense in the context 
/// (e.g., 12/0 is perfectly legal, but has an undefined value) 
/// </summary> 
static Regex RationalNumberPattern = new Regex(@" 
    ^     # anchor the start of the match at the beginning of the string, then... 
    (?<numerator>-?\d+) # match the numerator, an optionally signed decimal integer 
          # consisting of an optional minus sign, followed by one or more decimal digits), then... 
    /     # match the solidus (fraction separator, vinculum) that separates numerator from denominator 
    (?<denominator>-?\d+) # match the denominator, an optionally signed decimal integer 
          # consisting of an optional minus sign, followed by one or more decimal digits), then... 
    $      # anchor the end of the match at the end of the string 
    " , RegexOptions.IgnorePatternWhitespace);