sort array of strings by a part of these strings

Question

I am attempting to sort xls lines by fourth string in lines.

string[] list_lines = System.IO.File.ReadAllLines(@"E:\VS\WriteLines.xls");



        // Display the file contents by using a foreach loop.
        System.Console.WriteLine("Contents of Your Database = ");

        foreach (var line in list_lines)
        {

            // Use a tab to indent each line of the file.
            Console.WriteLine("\t" + line);
        }

I am having problems creating algorithm that will identify the fourth element of each line and list content in alphabetical order. The words in each line are separated by ' '.

Can anyone put me on a right direction please?

EDIT-------------------------- ok,

foreach (var line in list_lines.OrderBy(line => line.Split(' ')[3]))

sorted the problem. Lines are sorted as I need. Excel changes ' ' spaces with ';'. That's why when compiled it was giving error.

Now, I guess, I need to parse each part of string to int since it sorts by first digit and not by a number.

What do you want to do when a string doesn't have a 4th item, as found in @Patrick Hofman 's answer? — Draken
– Draken, Commented Apr 13, 2016 at 10:44
it's strange. I am sure that xls file is populated in 5 columns — paddy
– paddy, Commented Apr 13, 2016 at 10:46
They are probably being separated by another symbol than space. Have you check the lines while debugging? — Draken
– Draken, Commented Apr 13, 2016 at 10:47
Draken, You were right. It seems that excel puts ';' on place of empty spaces. — paddy
– paddy, Commented Apr 13, 2016 at 10:51

Patrick Hofman · Accepted Answer · 2016-04-13 10:37:50Z

1

You can split the lines and then use the third item in an OrderBy:

foreach (var line in list_lines.OrderBy(line => line.Split(' ')[3]))
{
}

answered Apr 13, 2016 at 10:37

Patrick Hofman

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3 Comments

paddy Over a year ago

thank you for your advice. Your code doesn't cause error, but when compiled I get strange error and code doesn't work.

Patrick Hofman Over a year ago

Then not every line has a fourth item.

paddy Over a year ago

they do, there are 5 columns in the file. all populated by numbers.

Dmitrii Bychenko · Accepted Answer · 2016-04-13 10:48:14Z

1

Well, just sort the array:

string[] list_lines = ...;

// General case: not all strings have 4 parts
Array.Sort(list_lines, (left, right) => {
  String[] partsLeft = left.Split(' ');
  String[] partsRight = right.Split(' ');

  if (partsLeft.Length < 4)
    if (partsRight.Length < 4)
      return String.Compare(left, right, StringComparison.OrdinalIgnoreCase) 
    else 
      return -1;
  else if (partsRight.Length < 4)
    return 1; 

  return String.Compare(partsLeft[3], partsRight[3], StringComparison.OrdinalIgnoreCase);
});

If all the lines guaranteed to have 4 items at least it can be simplfied into

Array.Sort(list_lines, (left, right) => 
  String.Compare(left.Split(' ')[3],
                 right.Split(' ')[3],
                 StringComparison.OrdinalIgnoreCase));

edited Apr 13, 2016 at 10:48

answered Apr 13, 2016 at 10:42

Dmitrii Bychenko

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