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C# SelectMany Example

SelectMany collapses many elements into a single collection. The resulting collection is of another element type. We specify how an element is transformed into a collection of other elements.

Select

Example. To start, this program uses an array of string literals. Then, the SelectMany method is used on this array. The argument to SelectMany is a Func lambda expression. It specifies that each string should be converted to a character array.

Finally: SelectMany combines all those character arrays and we loop over each char.

String LiteralFuncChar ArrayToCharArray
C# program that uses SelectMany method

using System;
using System.Linq;

class Program
{
    static void Main()
    {
	// Input.
	string[] array =
	{
	    "dot",
	    "net",
	    "perls"
	};

	// Convert each string in the string array to a character array.
	// ... Then combine those character arrays into one.
	var result = array.SelectMany(element => element.ToCharArray());

	// Display letters.
	foreach (char letter in result)
	{
	    Console.WriteLine(letter);
	}
    }
}

Output

d
o
t
n
e
t
p
e
r
l
s


Discussion. Any time you can change an element into an array or collection of parts, you can use SelectMany to simplify data. If you have an array of strings separated by delimiters, you can use SelectMany after splitting them.

Then: The final result is an array of all the individual parts of all the strings.

String ArraySplit

Summary. This method collapses a collection of elements. It yields a flattened representation of elements. We simplify data representations by transforming each element into its parts. We then access those parts in an IEnumerable collection.