用一個唯一值替換字符串中的每個單詞的實例

Question

在一個字符串中，我試圖用不同的值更新同一單詞的多個實例。

這是一個過於簡單的例子，但鑑於以下字符串：

"The first car I saw was color, the second car was color and the third car was color" 

字的顏色我想用「紅」，二審應該是「綠色」和更換的第一個實例第三例應該是「藍色」。

我想要嘗試的是尋找綁定單詞的正則表達式模式，通過循環進行交互並逐個替換它們。請參閱下面的示例代碼。

var colors = new List<string>{ "reg", "green", "blue" }; 
var sentence = "The first car I saw was color, the second car was color and the third car was color"; 

foreach(var color in colors) 
{ 
    var regex = new Regex("(\b[color]+\b)"); 
    sentence = regex.Replace(sentence, color, 1); 
} 

但是，「顏色」一詞永遠不會被替換爲適當的顏色名稱。我找不到我做錯了什麼。

Answer 1

試試比賽代表。

這是Regex.Replace（）的一個重載，大多數人都錯過了。它只是讓你定義一個潛在的上下文敏感的動態處理程序，而不是硬編碼的字符串來代替，並且可能有副作用。 「i ++％」是一個模運算符，下面用它來簡單循環訪問這些值。你可以使用數據庫或哈希表或任何東西。

var colors = new List<string> { "red", "green", "blue" }; 
var sentence = "The first car I saw was color, the second car was color and the third car was color"; 
int i = 0; 
Regex.Replace(sentence, @"\bcolor\b", (m) => { return colors[i++ % colors.Count]; }) 

該解決方案適用於任意數量的替換，這是更典型的替換（全局替換）。

Answer 2

我儘量遠離正則表達式。它有它的地方，但不是簡單的情況下，像這樣恕我直言:)

public static class StringHelpers 
{ 
    //Copied from http://stackoverflow.com/questions/141045/how-do-i-replace-the-first-instance-of-a-string-in-net/141076#141076 
    public static string ReplaceFirst(this string text, string search, string replace) 
    { 
     int pos = text.IndexOf(search); 
     if (pos < 0) 
     { 
      return text; 
     } 
     return text.Substring(0, pos) + replace + text.Substring(pos + search.Length); 
    } 
} 


var colors = new List<string>{ "red", "green", "blue" }; 
string sentence = colors.Aggregate(
    seed: "The first car I saw was color, the second car was color and the third car was color", 
    func: (agg, color) => agg.ReplaceFirst("color", color)); 

Answer 3

的問題是，在你的榜樣，color並不總是前面和後面一個非單詞字符。爲了您的例如，這個工作對我來說：

var regex = new Regex("\b?(color)\b?"); 

所以這樣的：

var colors = new List<string>{ "red", "green", "blue" }; 
var sentence = "The first car I saw was color, the second car was color and the third car was color"; 

foreach(var color in colors) 
{ 
    var regex = new Regex("\b?(color)\b?"); 
    sentence = regex.Replace(sentence, color, 1); 
} 

產生以下：

第一輛車我看到的是紅色的，第二輛車是綠和第三個 車是藍色的