在 C# 中将列表转换为字符串

Question

How do I convert a list to a string in C#?

When I execute toString on a List object, I get:

System.Collections.Generic.List`1[System.String]

Answer 1

Maybe you are trying to do

string combindedString = string.Join( ",", myList.ToArray() );

You can replace "," with what you want to split the elements in the list by.

Edit : As mention in the comments you could also do

string combindedString = string.Join( ",", myList);

Reference:

Join<T>(String, IEnumerable<T>) 
Concatenates the members of a collection, using the specified separator between each member.

Answer 2

我将根据我的直觉，假设您想要连接对列表的每个元素调用ToString的结果。

var result = string.Join(",", list.ToArray());

Answer 3

You could use string.Join :

List<string> list = new List<string>()
{
    "Red",
    "Blue",
    "Green"
};

string output = string.Join(Environment.NewLine, list.ToArray());    
Console.Write(output);

The result would be:

Red    
Blue    
Green

As an alternative to Environment.NewLine , you can replace it with a string based line-separator of your choosing.

Answer 4

If you want something slightly more complex than a simple join you can use LINQ eg

var result = myList.Aggregate((total, part) => total + "(" + part.ToLower() + ")");

Will take ["A", "B", "C"] and produce "(a)(b)(c)"

Answer 5

String.Join(" ", myList) or String.Join(" ", myList.ToArray()) . The first argument is the separator between the substrings.

var myList = new List<String> { "foo","bar","baz"};
Console.WriteLine(String.Join("-", myList)); // prints "foo-bar-baz"

Depending on your version of .NET you might need to use ToArray() on the list first..

Answer 6

You have a List<string> - so if you want them concatenated, something like

string s = string.Join("", list);

would work (in .NET 4.0 at least). The first parameter is the delimiter. So you could also comma-delimit etc.

You might also want to look at using StringBuilder to do running concatenations, rather than forming a list.

Answer 7

The .ToString() method for reference types usually resolves back to System.Object.ToString() unless you override it in a derived type (possibly using extension methods for the built-in types). The default behavior for this method is to output the name of the type on which it's called. So what you're seeing is expected behavior.

You could try something like string.Join(", ", myList.ToArray()); to achieve this. It's an extra step, but it could be put in an extension method on System.Collections.Generic.List<T> to make it a bit easier. Something like this:

public static class GenericListExtensions
{
    public static string ToString<T>(this IList<T> list)
    {
        return string.Join(", ", list);
    }
}

(Note that this is free-hand and untested code. I don't have a compiler handy at the moment. So you'll want to experiment with it a little.)

Answer 8

It's hard to tell, but perhaps you're looking for something like:

var myString = String.Join(String.Empty, myList.ToArray());

This will implicitly call the ToString() method on each of the items in the list and concatenate them.

Answer 9

The direct answer to your question is String.Join as others have mentioned.

However, if you need some manipulations, you can use Aggregate :

List<string> employees = new List<string>();
employees.Add("e1");
employees.Add("e2");
employees.Add("e3");

string employeesString = "'" + employees.Aggregate((x, y) => x + "','" + y) + "'";
Console.WriteLine(employeesString);
Console.ReadLine();

Answer 10

If you're looking to turn the items in a list into a big long string, do this: String.Join("", myList) . Some older versions of the framework don't allow you to pass an IEnumerable as the second parameter, so you may need to convert your list to an array by calling .ToArray().

Answer 11

This method helped me when trying to retrieve data from Text File and store it in Array then Assign it to a string avariable.

string[] lines = File.ReadAllLines(Environment.CurrentDirectory + "\\Notes.txt");  
string marRes = string.Join(Environment.NewLine, lines.ToArray());

Hopefully may help Someone!!!!

Answer 12

这似乎对我有用。

var combindedString = new string(list.ToArray());

Answer 13

如果您的列表具有字段/属性并且您想使用特定值（例如名字），那么您可以这样做：

string combindedString = string.Join( ",", myList.Select(t=>t.FirstName).ToArray() );

Answer 14

string strs="111,222,333"
string.Join(",",strs.Split(',').ToList().Select(x=>x.PadLeft(6,'0')).ToArray());

The output

000111,000222,000333