Linq with jagged arrays

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I am trying to understand a piece of code but I am not sure I do. I will be very grateful if someone could explain to me what happens here:

C#

foreach (var row in jaggedArray.Skip(1).OrderBy(r => r[headerIndex]))
{
    Console.WriteLine(string.Join(" | ", row));
}

What I have tried:

I suggest that .Skip(1) misses the first row, but after that, I did not understand anything. I will give you an example of what this code does:

4
name, age, grade
Peter, 25, 5.00
George, 34, 6.00
Marry, 28, 5.49
sort name

This is an example input. Our jagged array has 4 rows and 3 columns. We have to sort the name header so in this case, the header index is equal to 0. Thank you advance!

Posted 19-Jun-19 8:11am

Member 14422952

Updated 19-Jun-19 8:24am

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Thomas Daniels · Accepted Answer · 2019-06-19T08:24:00

OrderBy orders all elements in an enumerable by a certain key. In your example, the "elements" are arrays, and the "key" is the Nth element in the array (where N depends on headerIndex).

Here's an example:

C#

object[][] jaggedArray = new object[][] {
    new object[] { "Apples", 3.5, 200 },
    new object[] { "Bananas", 4.8, 50 },
    new object[] { "Ananas", 5.7, 75 }
}; // array of items in a store, with their name, price, and number in stock

var headerIndex = 0; // 0 for name, 1 for price, 2 for stock
foreach (var row in jaggedArray.Skip(1).OrderBy(r => r[headerIndex]))
{
    Console.WriteLine(string.Join(" | ", row));
}

This prints:

Ananas | 5.7 | 75
Bananas | 4.8 | 50

Because the first item, Apples, gets skipped, and the other items are sorted by r[headerIndex] (which is r[0] in the example, so the item name).