Introducting Collections and Arrays
What is a Collection?
Def: Collection is a data type whose purpose is to group same type of data together. So you can deal with a lot obj at same time.
Why collection is crucial for real data:
- Real data normally comprises lots of objects (e.g. sales, employees)
- Collection let you treat lots of objects as one single object
Many collections are available in .NET, 3 types are introduced here:
The Array: a Fixed Size Ordered Collection
Reference:
Array Characteristics:
- Fixed size: size of array is fixed once de
- Ordered
Syntax:
string[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
Enumerating an Array
Use case: iterate through every element within array. Note array stores element in order
Syntax:
foreach (var car in cars)
{
Console.WriteLine(car);
}
Some Collection Terminology
- Element (Item): an object (or struct) in a collection
- Enumerate: Go through each item in turn