C# - IEnumerable 到分隔字符串
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/167129/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
C# - IEnumerable to delimited string
提问by Jeremy
What is the functional programming approach to convert an IEnumerable<string>to a delimited string? I know I can use a loop, but I'm trying to wrap my head around functional programming.
将 an 转换IEnumerable<string>为分隔字符串的函数式编程方法是什么？我知道我可以使用循环，但我正在尝试围绕函数式编程。
Here's my example:
这是我的例子：
var selectedValues =
from ListItem item in checkboxList.Items
where item.Selected
select item.Value;
var delimitedString = ??
.. or could I do this in just the first var assignment (append each result to the previous)?
.. 或者我可以在第一个 var 赋值中做到这一点（将每个结果附加到前一个）？
采纳答案by Ilya Ryzhenkov
var delimitedString = selectedValues.Aggregate((x,y) => x + ", " + y);
回答by Tom Ritter
string.Join(", ", string[] enumerable)
回答by yfeldblum
var delimitedString = string.Join(",", checkboxList.Items.Where(i => i.Selected).Select(i => i.Value).ToArray());
回答by Marc Gravell
Well, in this case the functional approach might not be best suited, simply because there isn't a LINQ "ForEach", and you don't want to use string concatenation: you want to use StringBuilder. You could use ToArray (an example just appeared above), but I'd be tempted to simply use:
好吧，在这种情况下，函数式方法可能不是最适合的，仅仅是因为没有 LINQ“ForEach”，并且您不想使用字符串连接：您想使用 StringBuilder。您可以使用 ToArray （上面刚刚出现的示例），但我很想简单地使用：
StringBuilder sb = new StringBuilder();
foreach(ListViewItem item in checkboxList.SelectedItems) {
if(sb.Length > 0) sb.Append(',');
sb.Append(item.Text);
}
string s = sb.ToString();
Not functional programming, but it works... of course, if your source is alreadya string[] then string.Join is perfect. (LINQ is a great tool, but not necessarily always the best tool for every job)
不是函数式编程，但它有效……当然，如果您的源代码已经是 string[]，那么 string.Join 是完美的。（LINQ 是一个很棒的工具，但不一定总是适合每项工作的最佳工具）
回答by JaredPar
Here's a LINQ/functional way of doing it.
这是执行此操作的 LINQ/功能方式。
string[] toDelimit = CallSomeFunction();
return toDelimit.Aggregate((x, y) => x + "," + y);
回答by Santiago Palladino
AviewAnew is the best answer, but if what you are looking for is learning how to think in functional, what you should do is use a fold operation (or aggregate as it is called in NET).
AviewAnew 是最好的答案，但是如果您正在寻找的是学习如何在函数式中思考，那么您应该做的是使用折叠操作（或在 NET 中称为聚合）。
items.Aggregate((accum, elem) => accum + ", " + elem);
回答by Danko Durbi?
Here's an example with a StringBuilder. The nice thing is that Append()returns the StringBuilderinstance itself.
这是一个带有StringBuilder. 好消息是Append()返回StringBuilder实例本身。
return list.Aggregate( new StringBuilder(),
( sb, s ) =>
( sb.Length == 0 ? sb : sb.Append( ',' ) ).Append( s ) );
回答by UNeverNo
This is 3.5 compatible:
这是 3.5 兼容的：
var selectedValues = String.Join(",", (from ListItem item in checkboxList.Items where item.Selected select item.Value).ToArray());
