Using LINQ to convert a list to a CSV string

Question

I have a list of integers and I want to be able to convert this to a string where each number is separated by a comma.

So far example if my list was:

1
2
3
4
5

My expected output would be:

1, 2, 3, 4, 5

Is this possible using LINQ?

Thanks

Answer 1

In .NET 2/3

var csv = string.Join( ", ", list.Select( i => i.ToString() ).ToArray() );

or (in .NET 4.0)

var csv = string.Join( ", ", list );

• Timwi: Doesn’t work if list is a list of integers as specified in the question.
• tvanfosson: @Timwi - actually, it does in .NET 4, though, I forgot the fact that you no longer need an array, any enumerable will work.

Answer 2

Is this what you’re looking for?

// Can be int[], List<int>, IEnumerable<int>, ...
int[] myIntegerList = ...;
string myCSV = string.Join(", ", myIntegerList.Select(i => i.ToString()).ToArray());

Starting with C# 4.0, the extra mumbojumbo is no longer necessary, it all works automatically:

// Can be int[], List<int>, IEnumerable<int>, ...
int[] myIntegerList = ...;
string myCSV = string.Join(", ", myIntegerList);

• abatishchev: In fact, list should be IEnumerable because all other containers (you mentioned and not only they) inherits IEnumerable and Select is a method of IEnumerable
• Timwi: @abatishchev: The other containers implement IEnumerable, correct. The rest of what you said it wrong, especially the "list should be IEnumerable", but also the "Select is a method of IEnumerable" (and even if you had said IEnumerable<T>, it would still be wrong). It’s an extension method.
• tvanfosson: Actually, even the select as string isn't necessary as Join<T>( string, IEnumerable<T> ) will automatically convert each item in the enumerable to a string.
• abatishchev: @Timwi: Yes, I mean IEnumerable<T> - omitted just for short. Extension methods can't be in the air, they should be linked to some class and Select is linked to IEnumerable<T> See msdn.microsoft.com/en-us/library/bb548891.aspx "Enumerable Methods"
• Timwi: @abatishchev: I know all that. But there’s an important difference between IEnumerable and IEnumerable<T> and there’s an important difference between "a method of IEnumerable" (your wording) and an extension method.

Answer 3

string csv = String.Join(", ", list.Select(i=> i.ToString()).ToArray());

• Timwi: Technically, this answer does not produce the expected output as specified in the question ;-)

Answer 4

String.Join(", ", list); //in .NET 4.0

and

String.Join(", ", list 
 .Select(i => i.ToString()).ToArray()) //in .NET 3.5 and below

• Scott M.: your second statement makes no sense. it will give you a string array with one element.
• Yuriy Faktorovich: @Scott had an extra parantheses from my testing, fixed.