忽略空字符串的String.Join方法？

VB.NET方法String.Join(separator, stringArray)类似于PHP的implode，但是数组中的任何null元素都将替换为空字符串，因此：

Dim myArray() as String = { "a", null, "c" }
Console.WriteLine(String.Join(", ", myArray));
// Prints "a, , c"

有没有一种简单的方法可以用忽略空字符串的分隔符来连接一组字符串？

我不一定需要使用数组或String.Join或其他任何东西。我只需要进行以下转换：

("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（无需LINQ）中进行此操作（例如，对于SQL Server ReportingServices），而不必为其编写函数：

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＃（适用于从Google登陆但未搜索VB.NET的用户）

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);

这假定字符串中不会出现字符退格键（通常应为true，因为您不能简单地通过键盘输入此字符）。

另外，如果您从数据库中获取值，那么它甚至更简单，因为您可以直接在SQL中进行操作：

PostgreSQL和MySQL：

SELECT 
    concat_ws(' / '
        , NULLIF(searchTerm1, '')
        , NULLIF(searchTerm2, '')
        , NULLIF(searchTerm3, '')
        , NULLIF(searchTerm4, '')
    ) AS RPT_SearchTerms; 

即使使用了出色的MS-SQL-Server，也有可能（PS：这很讽刺）：

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 

请尝试以下操作：

var finalString = String.Join(",", ExampleArrayOfObjects.Where(x => !String.IsNullOrEmpty(x.TestParameter)).Select(x => x.TestParameter));

这对于VB.NET正常工作

Join(*yourArray*.Where(Function(s) Not String.IsNullOrEmpty(s)).ToArray(), *yourDelimiter*)