LINQ expression instead of nested foreach loop

Question

So i have List whose each element is a string array

List<string[]> TokenList = new List<string[]>();

I want to display each element in the array for every array in the list. and for that i use a nested foreach loop.

foreach (var temp in pro.TokenList)
        {
            foreach (var s in temp)
            {
                Console.WriteLine(s);
            }
        }

Now i am trying to use LINQ in my programs and i was wondering what kind of LINQ query would be used to achieve the same desired result.

Jeroen van Langen · Accepted Answer · 2013-08-26 19:56:33Z

8

I'd rather keep it simple:

// select all sub-strings of each TokenList into 1 big IEnumerable.
var query = pro.TokenList.SelectMany(item => item);

// display all strings while iterating the query.
foreach(var s in query)
    Console.WriteLine(s);

It's funny that people combine many statements, but it will be less readable.

edited Aug 26, 2013 at 19:56

answered Aug 26, 2013 at 19:47

Jeroen van Langen

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1 Comment

Servy Over a year ago

That has the advantage over the string.Join solutions of not bringing all of the strings into memory at the same time; it streams them to the output, thus resulting in earlier items being seen earlier, rather than waiting for the last item to be processed.

SLaks · Accepted Answer · 2013-08-26 19:44:24Z

4

Console.WriteLine(String.Join(Environment.NewLine, 
    pro.TokenList.SelectMany(s => s)
));

Or,

Console.WriteLine(String.Join(Environment.NewLine, 
    from arr in pro.TokenList
    from s in arr
    select s
));

answered Aug 26, 2013 at 19:44

SLaks

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5 Comments

Win Coder Over a year ago

ummm appreciate the answer but could it be in the form of a query ?

SLaks Over a year ago

@WinCoder: Queries can only be used to query data, not take side-effects. Or do you mean query comprehension syntax as opposed to direct extension method calls?

Win Coder Over a year ago

yup query comprehension syntax

SLaks Over a year ago

@WinCoder: Here you go.

Win Coder Over a year ago

ahhh that's better now to understand it.

Michael · Accepted Answer · 2013-08-26 19:45:13Z

2

Try to do this:

Console.WriteLine(String.Join(Environment.NewLine, 
    pro.TokenList.SelectMany(s => s)
));

This should work. If it doesn't add a comment :)

answered Aug 26, 2013 at 19:45

Michael

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Comments

BartoszKP · Accepted Answer · 2013-08-26 19:53:32Z

-2

pro.TokenList.ForEach(temp => Array.ForEach(temp, Console.WriteLine));

However not much LINQ here ;), as noted in the comments, just more concise :) Also, as noted by Servy under the other answer - this also has the advantage of not joining and storing all the strings in memory again.

edited Aug 26, 2013 at 19:53

answered Aug 26, 2013 at 19:46

BartoszKP

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