如何將嵌套for循環與if條件轉換爲LINQ

Question

我有一個可怕的方法，從DataTable中提取數據並將其轉換爲所需格式的DataTable。我相信在LinQ中有更好的方法來做到這一點，但我並沒有真正體驗過它。如果有人能給我一個更好的解決方案，我將不勝感激。

赫雷什代碼

private static void ExtractImportLayoutFromExcelDt(DataTable importDt, DataTable dtExtracted, int languages) 
    { 
     // The number of Locale colums included in the excel file. 
     for (int x = 0; x < languages; x++) 
     { 
      // The total number of friendlynames-keys/language included in the excel. 
      for (int j = 0; j < dtExtracted.Rows.Count; j++) 
      { 
       var row = dtExtracted.Rows[j]; 
       DataRow tempRow = importDt.NewRow(); 
       // Filling in the 3 columns. (FriendlyName - LocaleID - Text) 
       for (int i = 0; i <= 2; i++) 
       { 
        if (i == 0) 
        { 
         tempRow[i] = row[i];  // Friendly names: This is always going to be column 1 [0].       
        } 
        else if (i == 1) 
        { 
         tempRow[i] = Regex.Match(dtExtracted.Columns[x + 1].ToString(), @"\d+").Value; // LocaleIDs: Getting rid of non numeric characters from this column. 
        } 
        else 
        { 
         tempRow[i] = row[x + 1]; 
        } 
       } 
       importDt.Rows.Add(tempRow); 
      } 
     } 
    } 

Answer 1

我將重寫內for環路

for (int x = 0; x < languages; x++)  
    foreach (DataRow row in dtExtracted.Rows)   
     importDt.Rows.Add 
     (
      row[0], 
      Regex.Match(dtExtracted.Columns[x + 1].ToString(), @"\d+").Value; // LocaleIDs: Getting rid of non numeric characters from this column. 
      row[x + 1] 
     ); 

DataTable.Rows集合具有Add方法，該方法接受對象的陣列的過載：Add

Answer 2

我不很確定LINQ是否可以在這裏得到任何幫助，但除了重寫整個映射邏輯之外，我會這樣做至少這個方法分爲兩個：

private static void ExtractImportLayoutFromExcelDt(DataTable importDt, DataTable dtExtracted, int languages) 
    { 
     // The number of Locale colums included in the excel file. 
     for (int x = 0; x < languages; x++) 
     { 
      // The total number of friendlynames-keys/language included in the excel. 
      for (int j = 0; j < dtExtracted.Rows.Count; j++) 
      { 
       AddRow(importDt, dtExtracted, dtExtracted.Rows[j], x+1); 
      } 
     } 
    } 

    private static void AddRow(DataTable table, DataTable dtExtracted, DataRow originalRow, int language) 
    { 
     var row = table.NewRow(); 
     row[0] = originalRow[0]; 
     row[1] = Regex.Match(dtExtracted.Columns[language].ToString(), @"\d+").Value; 
     row[2] = originalRow[language]; 
     table.Rows.Add(row); 
    } 

Answer 3

你可以寫這樣的事情，但是在這種情況下更像是Linq的濫用，但如果你對教育目的做LINQ的..The主要動力是，當你想枚舉或過濾例如集合，而不是像這樣的情況。

public static void ExtractImportLayoutFromExcelDt(DataTable importDt, DataTable dtExtracted, int languages) 
    { 
     Enumerable.Range(0, languages) 
      .ToList().ForEach(x => 
      { 
       Enumerable.Range(0, dtExtracted.Rows.Count) 
        .ToList().ForEach(j => 
        { 
         var row = dtExtracted.Rows[j]; 
         DataRow tempRow = importDt.NewRow(); 
         AddRow(importDt, dtExtracted, x, row, tempRow); 
        }); 
      }); 
    } 

    private static void AddRow(DataTable importDt, DataTable dtExtracted, int x, DataRow row, DataRow tempRow) 
    { 
     for (int i = 0; i <= 2; i++) 
     { 
      if (i == 0) 
      { 
       tempRow[i] = row[i];  // Friendly names: This is always going to be column 1 [0].       
      } 
      else if (i == 1) 
      { 
       tempRow[i] = Regex.Match(dtExtracted.Columns[x + 1].ToString(), @"\d+").Value; // LocaleIDs: Getting rid of non numeric characters from this column. 
      } 
      else 
      { 
       tempRow[i] = row[x + 1]; 
      } 
     } 
     importDt.Rows.Add(tempRow); 
    }