C# Is there a loop-free way to write an array?

Question

Something like

char[] a = new char[] { 'a', 'b', 'c', 'd' };<br>
Console.WriteLine(a);

works nicely with C#. If the type of the array is integer this does not work any longer. It has to be coded as

for (int k = 0; k < a.Length; k++) Console.Write(a[k]); Console.WriteLine();

This looks rather lame to me. Is there a more succinct way to do so? For example some way which expands WriteLine(a) in a loop-free way to

WriteLine("{0},{1},{2},...,{a.Length-1}", a[0],a[1],a[2],...,a[a.Length-1]);

Perhaps there is some neat Linq trick?

I am looking for a substitute in the case that it is /not/ a char[]. — Johnathan
– Johnathan, Commented Jul 31, 2010 at 11:59
From the look of it, no. The OP is looking for a way that'll work with arrays of any (primitive, at least) type. — cHao
– cHao, Commented Jul 31, 2010 at 11:59
Three reasons to switch to Java: (1) toString(arr) is more idiomatic, (2) it's there since Java 5, released in 2004, (3) your question gets 13 points, gimel's answer 32 points on SO (question 409784). — John
– John, Commented Aug 1, 2010 at 11:58

Community · Accepted Answer · 2020-06-20 09:12:55Z

10

How about String.Join ? Beginning with .Net Framework 4, the second argument is an object[]:

String.Join Method (String, Object[])

Concatenates the elements of an object array, using the specified separator between each element.

Trying a snippet in Visual Studio 2010, targeting framework 4:

    int[] a = new int[] {1,2,3,4,5,6,7 };
    Console.WriteLine(String.Join(",", a));

Produces:

1,2,3,4,5,6,7

edited Jun 20, 2020 at 9:12

CommunityBot

11 silver badge

answered Jul 31, 2010 at 12:12

gimel

86.9k10 gold badges80 silver badges104 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Matthew Whited · Accepted Answer · 2010-07-31 12:03:55Z

1

The .Aggregate<TSource, TAccumulate>(source, func) is your friend in this case. You can seed it with a StringBuilder and then just chain Appends from there. Most of the member methods on the StringBuilder class return an instance to the StringBuilder you passed in making it great to use in these types of scenarios.

Sample...

var charArray = new[] { 'a', 'b', 'c', 'd' };
var objectArray = new object[] { 'a', "Hello", 1, null };

Console.WriteLine(new string(charArray));
Console.WriteLine(objectArray.Aggregate(
    new StringBuilder(), 
    (sb,v)=>sb.Append(v+" ")));

Result ...

abcd
a Hello 1

edited Jul 31, 2010 at 12:03

answered Jul 31, 2010 at 11:57

Matthew Whited

22.5k4 gold badges54 silver badges69 bronze badges

Comments

ankitjaininfo · Accepted Answer · 2010-07-31 11:55:27Z

0

it works because of ToString() method. After all there is a loop inside toString() ! For any of your custom classes you can override toString method.

answered Jul 31, 2010 at 11:55

ankitjaininfo

12.4k7 gold badges54 silver badges76 bronze badges

Comments

mike nelson · Accepted Answer · 2010-07-31 11:56:14Z

0

I think you can use something like:

a.ForEach(e=>WriteLine(e))

answered Jul 31, 2010 at 11:56

mike nelson

22.2k14 gold badges72 silver badges76 bronze badges

1 Comment

Johnathan Over a year ago

There are two syntax errors, as far as I see. This works: Array.ForEach(a, e => Console.Write(e)); Console.WriteLine(); Which is not much better than the for-loop.

theburningmonk · Accepted Answer · 2010-07-31 11:57:28Z

0

You can use Enumerable.Select and Aggregate

var intArray = new[] { 1, 2, 3, 4 };

Console.WriteLine(intArray.Select(i => i.ToString())
                          .Aggregate((acc, item) => acc + "\n" + item));

This outputs:

answered Jul 31, 2010 at 11:57

theburningmonk

16.1k15 gold badges65 silver badges106 bronze badges

1 Comment

Martin Jonáš Over a year ago

This solution has one major problem. Since string is immutable type, new instance has to be created for each item of the list and therefore this algorithm has space complexity in O(n^2). You should use StringBuilder instead.

jeroenh · Accepted Answer · 2010-07-31 12:03:34Z

0

Enumerable.Range(0, 100).ToList().ForEach(Console.Write); Console.WriteLine();

The ForEach() method is specific for List<T>, but you can create your own extension method on IEnumerable<T> for this, if you want:

public static class MyExtensions
{
    public static void ForEach<T>(this IEnumerable<T> list, Action<T> action)
    {
       foreach (var item in list) action(item);
    } 
}

Now you can do this:

 Enumerable.Range(0, 100).ForEach(Console.Write);

edited Jul 31, 2010 at 12:03

answered Jul 31, 2010 at 11:57

jeroenh

26.9k11 gold badges77 silver badges107 bronze badges

3 Comments

Rup Over a year ago

You probably don't need the ToList

jeroenh Over a year ago

@Rup see my edit. If you dont want the ToList(), you need to add your own ForEach extension method on IEnumerable<T>.

Rup Over a year ago

Oops, forgot about that - sorry!

Merlyn Morgan-Graham · Accepted Answer · 2010-07-31 12:28:30Z

0

Confused as to what the OP is asking, since the sample code does two different things. One prints:

123456

The other prints:

1,2,3,4,5,6

If you want the second, use gimel's solution (using string.Join). If you want the first, here's the simplest method, which is easy to read, even for C# newbies, and will work even in C# 1.0:

foreach(object k in a)
    Console.Write(k);

Why over complicate such a simple thing? While this is not "loop-free", it is just as concise as the rest of them. The rest are still loops, they're just hidden by syntax :)

answered Jul 31, 2010 at 12:28

Merlyn Morgan-Graham

59.4k16 gold badges131 silver badges189 bronze badges

3 Comments

Johnathan Over a year ago

For me gimel's Console.WriteLine(String.Join(",", a)) looks far better then any for or foreach-loop. And that there are also some bits and bytes hidden by the syntax does even yours truly newbie know.

Merlyn Morgan-Graham Over a year ago

@Johnathan: I guess the point I was making is that this 10 different ways to tie your shoes is little more than academic. Use the simplest and most obvious method available to you, as long as it doesn't make your program long/grotesque, and then everyone will understand your programs.

Merlyn Morgan-Graham Over a year ago

@Johnathan: Oh, also, I don't mean to bad mouth you, or new programmers :) I just meant it wasn't hidden behind any hocus-pocus.

Collectives™ on Stack Overflow

C# Is there a loop-free way to write an array?

7 Answers 7

Comments

Comments

Comments

1 Comment

1 Comment

3 Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

Comments

Comments

Comments

1 Comment

1 Comment

3 Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related