正則表達式C＃斷言字符串是分數

Question

所有，

我需要2個正則表達式，它可以在.NET來檢測用戶是否在一小部分類型：

1. 只有分數值沒有任何整部分（不想檢查1 1/4，3 1/2等） ONLY：1/2，3/4，8/3等。分子分母可以是浮點數或整數。

2. ALL有效餾分，例如1/3，2/3，1 1/4等

感謝。

Answer 1

對於第一

對於在##/##，其中分子或分母可以是任何長度形式的任何部分，你可以只使用：

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

抓住儘可能多的數字作爲您可以立即在字面斜槓前後，只要至少有一個或多個這些數字。如果有一個小數點，它也必須跟着一個或多個數字，但整個組是可選的，只能出現一次。

對於第二

假設它必須是一小部分，因此整體人數就喜歡1起不到作用，只要堅持正面

\d*\s* 

抓住以下一些數字並在其餘部分之前留出空白。

Answer 2

試試這個：

/// <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);