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C# Beyond Basics
C# Beyond Basics
What are Lists?
Imagine we have a situation where we want to store the names of all the students that are taking a certain course. The first solution we can come up is to create an Array:
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However, if at some point are more than 50 students, we won't be able to store their names. Similarly, in a situation where there are less than 50 students, the unoccupied spaces in the array will be a waste of memory - this becomes a problem in especially large arrays.
Here we need a new structure which can store a variable amount of elements. Luckily such a structure already exists, it's called a List.
Lists are very similar to Arrays, however the number of elements that are stored in a list are changeable.
Following is the syntax for declaring an empty list:
Using this syntax we can create a list for storing the Students' names:
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It is important to note that we need to import the Generic
module to be able to use Lists.
You simply need to add this line under using System;
to import the required module.
Add() Method
We can add elements to a list by using the Add
method:
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The above code will add four elements to the students
list.
Just like an Array of type string
can only contain string
elements. A list of type string
can only accept string
elements.
Indexing
The first element is Anna
hence it will have the index 0
, while Laura
will have the index 1
and so on. Elements of a list can be accessed via indexing just like an array:
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Count() Method
We can retrieve the length of a list using its Count
attribute:
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Dynamic Length
Note that the length of a list is dynamic (changeable), so it changes as we add elements:
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Initialization
We can also initialize a list with some elements using the following syntax:
For-example:
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Looping Through Lists
Looping through a List similar to how we would loop through Arrays
- Using a for-loop:
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- Using a foreach loop
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Tip:
To make the declaration syntax shorter we can also use implicit declaration. To recall, an explicit declaration is when we specify the data type during variable declaration, for-example:
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On the other hand, in implicit declaration we can simply use the var
keyword and the compiler automatically infers the data type of the variable according to the assigned value:
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We can use implicit declaration when declaring lists as well:
For-example:
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