Question

VB.NET方法String.Join(separator, stringArray)类似于PHP的内爆，但数组中的任何null元素都替换为空字符串，因此c：

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

是否有一种简单的方法可以将一组字符串与一个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。我只需要进行以下转换：

("a", "b", "c") --> "a, b, c"
("a", null, "c") --> "a, c"

Answer 1

<强> VB.NET

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

<强> C＃

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

Answer 2

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

Answer 3

在.NET 2.0（无LINQ）中执行此操作，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＃（对于那些从谷歌登陆而不是搜索VB.NET的人）

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);

这假设字符退格不会出现在你的字符串中（通常应该是真的，因为你不能通过键盘输入这个字符）。

此外，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中执行此操作：

PostgreSQL＆amp; MySQL：

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

即使拥有光荣的MS-SQL-Server也是可能的（PS：那个讽刺）：

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

Answer 4

尝试以下操作：

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

Answer 5

这对于 VB.NET

很好

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

String.Join忽略空字符串的方法？

5 个答案: