String.Join忽略空string的方法？
VB.NET方法String.Join(separator, stringArray)类似于PHP的implode，但是数组中的所有null元素被replace为一个空string，所以thatc：
Dim myArray() as String = { "a", null, "c" } Console.WriteLine(String.Join(", ", myArray)); // Prints "a, , c"
有没有简单的方法来连接一组string与忽略空string的分隔符？
我不一定需要使用数组或String.Join或其他任何东西。 我只需要以下转换：
("a", "b", "c") --> "a, b, c" ("a", null, "c") --> "a, c"
VB.NET
String.Join(",", myArray.Where(Function(s) Not String.IsNullOrEmpty(s)))
C＃
String.Join(",", myArray.Where(s => !string.IsNullOrEmpty(s)))
对于C＃==> String.Join(",", arr.Where(s => !String.IsNullOrEmpty(s)));
要在.NET 2.0（无LINQ）中执行，例如SQL-Server ReportingServices，无需为其编写函数：
VB.NET
Dim a As String = "", b As String = "b", c As String = "", d As String = "d", e As String = "" Dim lala As String = String.Join(" / ", String.Join(vbBack, New String() {a, b, c, d, e}).Split(New Char() {ControlChars.Back}, System.StringSplitOptions.RemoveEmptyEntries)) System.Console.WriteLine(lala)
C＃（对于那些从谷歌login和不searchVB.NET）
string a = "", b = "b", c = "", d = "d", e = ""; string lala = string.Join(" / ", string.Join("\u0008", new string[] { a, b, c, d, e } ).Split(new char[] { '\u0008' }, System.StringSplitOptions.RemoveEmptyEntries) ); System.Console.WriteLine(lala);
这假定字符退格不会出现在你的string中（通常应该是真的，因为你不能简单地通过键盘input这个字符）。
另外，如果您从数据库中获取值，则更简单，因为您可以直接在SQL中执行此操作：
PostgreSQL和MySQL：
SELECT concat_ws(' / ' , NULLIF(searchTerm1, '') , NULLIF(searchTerm2, '') , NULLIF(searchTerm3, '') , NULLIF(searchTerm4, '') ) AS RPT_SearchTerms;
即使有光荣的MS-SQL服务器，这是可能的（PS：这是讽刺）：
DECLARE @in_SearchTerm1 nvarchar(100) DECLARE @in_SearchTerm2 nvarchar(100) DECLARE @in_SearchTerm3 nvarchar(100) DECLARE @in_SearchTerm4 nvarchar(100) SET @in_SearchTerm1 = N'a' SET @in_SearchTerm2 = N'' SET @in_SearchTerm3 = N'c' SET @in_SearchTerm4 = N'' SELECT COALESCE ( STUFF ( ( SELECT ' / ' + RPT_SearchTerm AS [text()] FROM ( SELECT NULLIF(@in_SearchTerm1, N'') AS RPT_SearchTerm, 1 AS RPT_Sort UNION ALL SELECT NULLIF(@in_SearchTerm2, N'') AS RPT_SearchTerm, 2 AS RPT_Sort UNION ALL SELECT NULLIF(@in_SearchTerm3, N'') AS RPT_SearchTerm, 3 AS RPT_Sort UNION ALL SELECT NULLIF(@in_SearchTerm4, N'') AS RPT_SearchTerm, 4 AS RPT_Sort ) AS tempT WHERE RPT_SearchTerm IS NOT NULL ORDER BY RPT_Sort FOR XML PATH(N''), TYPE ).value('.', 'nvarchar(MAX)') ,1 ,3 ,N'' ) ,N'' ) AS RPT_SearchTerms
