c# - 错误消息：无法从 'System.Collections.Generic.IEnumerable' 转换为 'string[]'

Question

我有以下 C# 源代码：（asp.net 版本：3.5）

 //map is from 'string' type
 map = string.Join("", TrackMap.Split('|').Select(x => string.Format("<a href=\"{0}\" class=\"lightview\"><img src=\"{0}\" style=\"margin-right:30px;\" width=\"120\" height=\"80\"/>gh</a>", x)));

问题是我收到此错误消息：

参数“2”：无法从“System.Collections.Generic.IEnumerable”转换为“string[]”

和错误信息：

'string.Join(string, string[])' 的最佳重载方法匹配有一些无效参数

我的问题是我该如何解决？（也许在 web.config 文件中添加一些代码？添加“使用”-someting？）

Answer 1

Since you are in .NET 3.5 which has not yet supported Join<T>(String, IEnumerable<T>), but supports Join(String, Object[]), so, you just need to call ToArray method in order to convert IEnumerable to Array:

map = string.Join("", TrackMap.Split('|').Select(x => string.Format("...", x))
                                         .ToArray());

Answer 2

string.Join with the overload that takes an IEnumerable<String> was new in .NET 4, so you cannot use it in 3.5.

So this should work:

map = string.Join("", TrackMap.Split('|')
            .Select(x => string.Format("<a href=\"{0}\" class=\"lightview\"><img src=\"{0}\" style=\"margin-right:30px;\" width=\"120\" height=\"80\"/>gh</a>", x)
            .ToArray()));