如何将IEnumerable <char>转换为string []，以便我可以将它与String.Join一起使用？

Question

如何将IEnumerable<char>“nonLetters”转换为string[]，以便我可以在String.Join中使用它？

string message = "This is a test message."; 

var nonLetters = message.Where(x => !Char.IsLetter(x)); 

Console.WriteLine("There are {0} non-characters in \"{1}\" and they are: {2}", 
    nonLetters.Count(), 
    message, 
    String.Join(", ", nonLetters.ToArray()) 
    ); 

Answer 1

string[] foo = nonLetters.Select(c => c.ToString()).ToArray(); 

Answer 2

string result = new string(nonLetters.ToArray()); //convert to a string 

我才意识到你想有一个字符串[]而不是字符串：

string[] result = nonLetters.Select(c => new string(new[] { c })).ToArray(); 

讨厌。但它的工作原理...

Answer 3

只需为每个非字母选择一个字符串而不是字符。

String() nonLetters = message.Where(x => !Char.IsLetter(x)) 
          .Select(x => x.ToString()) 
          .ToArray(); 

Answer 4

我想你想：

string message = "This is a test message."; 

var nonLetters = message.Where(x => !Char.IsLetter(x)); 

Console.WriteLine("There are {0} non-characters in \"{1}\" and they are: {2}", 
    nonLetters.Count(), 
    message, 
    String.Join(", ", nonLetters.Select(x => x.ToString()).ToArray()) 
    ); 

所有我所做的是对的的string.join通话nonLetters通话Select(x => x.ToString())。似乎工作。

Answer 5

如果你不真正关心使用的string.join但只想要的结果，使用新的字符串（的char []）是最简单的变化：

string message = "This is a test message."; 
var nonLetters = message.Where(x => !Char.IsLetter(x)); 
Console.WriteLine("There are {0} non-characters in \"{1}\" and they are: {2}", 
    nonLetters.Count(), 
    message, 
    new string(nonLetters.ToArray())); 

但你的例子是如果你做这种方式更有效：

string message = "This is a test message."; 
string nonLetters = new string(message.Where(x => !Char.IsLetter(x)).ToArray()); 
Console.WriteLine("There are {0} non-characters in \"{1}\" and they are: {2}", 
    nonLetters.Length, 
    message, 
    nonLetters); 

的原因，这是更有效的是，其他示例循环您其中迭代两次：一次是对count（）调用，其他时间F或ToArray（）调用。

Answer 6

With .NET 4 you have another overload for Join。就这么简单：

var nonLettersJoined = string.Join(", ", message.Where(x => char.IsLetter(x))); 

节省您的另一Select和ToArray一部分。所以应该更有效率..内部调用ToString。