117

VB.NET 的方法String.Join(separator, stringArray)类似于 PHP 的 implode，但数组中的任何 null 元素都替换为空字符串，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将一组字符串与忽略空字符串的分隔符连接起来？

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"
4

5 回答 5

202

VB.NET

String.Join(",", myArray.Where(Function(s) Not String.IsNullOrEmpty(s)))

C＃

String.Join(",", myArray.Where(s => !string.IsNullOrEmpty(s)))

于 2013-05-01T20:36:50.910 回答
59

对于 C# == > String.Join(",", arr.Where(s => !String.IsNullOrEmpty(s)));

于 2015-01-08T09:40:46.750 回答
4

要在 .NET 2.0（无 LINQ）中执行此操作，例如用于 SQL-Server ReportingServices 而无需为其编写函数：

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#（适用于从谷歌登陆而不搜索 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);

这假设您的字符串中没有出现退格字符（通常应该是正确的，因为您不能简单地通过键盘输入此字符）。

此外，如果您从数据库中获取值，那么它会更简单，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;

即使使用光荣的 MS-SQL-Server 也是可能的（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
于 2016-09-14T08:45:21.433 回答
-1

尝试以下操作：

var finalString = String.Join(",", ExampleArrayOfObjects.Where(x => !String.IsNullOrEmpty(x.TestParameter)).Select(x => x.TestParameter));
于 2018-08-14T12:24:40.917 回答
-1

这适用于VB.NET

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

于 2019-02-20T13:59:50.680 回答