Tip 1. using Enumerable.Range - generate a sequence
Flavor 1:
var list = Enmerable.Range(1,10) .ToList();
This is equivalent to the following code:
List list = new List();
for(int i=1; i<=10; i++)
{
list.Add(i);
}
Rather than writing 4 lines of code to generate a list of integers from 1 to 10, you can use Enumerable. Range.
Flavor 2
Another flavor of it is used in a situation when you need to iterate something for a fixed number of times:
for(int i=1; i<=10; i++)
{
Print("My name is printed " + i + " times");
}
This code can be replaced with following LINQ:
var list = Enumerable.Range(1,10).Select(item => "My name is printed " + item + " times").ToList();
AWESOME, isn't it?
Flavor 3:
Printing a table of 5:
var list = Enumerable.Range(1,10).Select(item => Console.WriteLn( (item*5).ToString()).ToList();
Flavour 4
In the following class House, there are rooms. Sat the situation is we want to print the room number against each room for all houses.
Here is the class structure:
class House
{
public string Name { get; set; }
public int Rooms;
}
var houses = new List<House>
{
new House{Name = "Condo", Rooms = 3},
new House{Name = "Villa", Rooms = 10}
};
In simple words, For each house, iterate to all rooms of this house and print room number.
So the algorithm is something like :
For each house in Houses
For j = 1 to house.Rooms.Count
print house.Name + "room numer " + j
EndFor
EndFor
Hence the simplest form of traditional code is :
var roomsIterate = new List();
foreach (var h in houses)
{
for (int i = 1; i < h.Rooms + 1; i++)
{
roomsIterate.Add(h.Name + " room number " + i);
}
}
But we can also reduce these lines of code using LINQ and Lambda:
var roomsLinq = houses.SelectMany(h => Enumerable.Range(1, h.Rooms).Select(i => h.Name + " room number " + i));
Flavor 5:
Enumerable.Range can be used to initialize the data class in a collection. For example:
List<House> houses = new List<House>();
for(int i = 0 i<=9 ; i++)
{
houses.Add( new House());
}
This code can be boiled in LINQ as :
List<House> houses = new List<House>(Enumerable.Range(1, 10).Select(item => new House());
You can think about likeEnumerable.Range a tool of retrieving a subset of a collection.
