C# - What is an array?

[kaddle]

to be clear, i learned the basics of arrays including the basics on using arrays and i have a complete understanding of those basics. my confusion is regarding the classification of an array. when i see and use arrays they are clearly like a special type of variable since arrays can store multiple values. the book i'm learning from deliberately classifies arrays as a "advanced data type" along with strings and lists in the same classification (i'm assuming because arrays, strings, and lists have properties and methods). 

 

so essentially i'm wondering why arrays would be mentioned as being advanced data type along with strings and lists.

[tarfeef101]

A variable is simply an instance of a data type. Let me give an example.

String is a data type. So is integer. 
 

int x = 6

x is a variable, of type integer

 

String y = "abc"

y is a variable, of type string

 

int[] arr = {1, 2, 3}

arr is a variable, of type int array


So it is not "more special" than any other data type

[Jurrunio]

array isnt special. You won't say a 14-alphabet long word is special to a 3-alphabet one right?

[straight_stewie]

39 minutes ago, kaddle said:

"special data type" along with strings and lists in the same classification.  

I'd keep reading. I would bet that he's calling certain things "special types" because he's later going to explain classes and objects more thoroughly. If you're just now covering arrays, you're still at the beginning of the book (if not, get a better book).

Or, at the very least, is calling arrays "special" because it's "a variable that holds more than one thing".

 

What book are you reading?

[kaddle]

lol whoops, my bad. i went back to read the quote and it is actually written as "advanced data type". not special. i think this type of description was mainly a way of describing that the data types have more features than others since they have properties and methods. but not that the data type itself is a different type of data type. i'll also edit the OP. my only confusion is why arrays would be under the classification of data type along with strings and lists.

 

the book itself is treating me very well so far and i'm learning a lot. i'm still early on in the book.

 

Edit: the book i'm reading is "learn C# in one day and learn it well". i suppose i'm going through the book a bit slowly since i'm documenting all of the information in a comprehensive way for me (not copy paste). i'm also practicing some of the things i learn in visual studio which takes more time.

[straight_stewie]

50 minutes ago, kaddle said:

my only confusion is why arrays would be under the classification of data type along with strings and lists. 

In C#, there are two classifications of types: Reference types and Value types.

• Value types are passed around by creating a copy of the contents of the type and passing the copy to the function.
• Reference types are passed around by giving the "address" of the object to the function.

The builtin Array type is a reference type.

While it is true that "String" and "Array" are both reference types. That's about where the similarities end. The problem with classifying builtin types is that the compiler/runtime often make what can only be described as "special dispensations" for the builtin types. For our purposes, "special dispensation" means that the type exhibits behavior that cannot be recreated without modifying the compiler/runtime. For example, String is treated as a reference type in some ways, and treated as a value type in other ways.

For trivia, the definition of the Array type is here: System.Array

Also, arrays could be considered "special" in the sense that it is baked into the language. For example:

// this is the normal declaration of a 
// variable of type "non static reference type".
// this is not, however, how we get arrays.
Array<int> myArr = new Array<int>(10);

// Instead, the compiler makes a 
// "special dispensation" for System.Array
// For example:
int[] myArr = new int[10];

 

[kaddle]

On 2/25/2019 at 2:03 PM, straight_stewie said:

Actually, he's wrong there.

In C#, there are two classifications of types: Reference types and Value types.

• Value types are passed around by creating a copy of the contents of the type and passing the copy to the function.
• Reference types are passed around by giving the "address" of the object to the function.

The builtin Array type is a reference type.

While it is true that "String" and "Array" are both reference types. That's about where the similarities end. The problem with classifying builtin types is that the compiler/runtime often make what can only be described as "special dispensations" for the builtin types. For example, String is treated as a reference type in some ways, and treated as a value type in other ways.

For trivia, the definition of the Array type is here: System.Array

Also, arrays could be considered "special" in the sense that it is baked into the language. For example:

// this is the normal declaration of a 
// variable of type "non static class".
// this is not, however, how we get arrays.
Array<int> myArr = new Array<int>(10);

// Instead, the compiler makes a 
// "special dispensation" for System.Array
// For example:
int[] myArr = new int[10];

What book are you reading? If the author is really saying things like that, you should really consider getting a better book that contains less misinformation.

the book i'm reading is: learn c# in one day and learn it well.

 

i think what's happening in this thread is probably that i'm just bad at explaining what i'm talking about. sorry for that. it's written in the book that it will talk about value and reference types after explaining the basics about arrays, strings, and lists. i read the part about arrays already and i'm almost done reading the part about strings, so i did not reach the part where it explains about value and reference types. i can tell the book isn't perfect but so far it has been the most comprehensive learning material that i tried to learn c# from, so i'm not sure that the book is the problem. i suppose i'll have a better idea once i read more pages. the only bit of confusion i have is the way arrays were described in the book.

 

Spoiler

it says that an array is an advanced data type, but in the part about arrays it says the square commas indicate that the variable is an array instead of a normal variable. so i'm confused about how it can be a data type and also be a variable at the same time. so maybe i'm just confused because i'm still new to C#? it sort of makes sense in the context that a variable is an instance of a data type, as someone explained above. yet at the same time a variable itself is a storage container, while the data type is the type of data being stored.

 

[straight_stewie]

18 minutes ago, kaddle said:

so i'm confused about how it can be a data type and also be a variable at the same time.

I had the same problem when I was starting out as well. I found it hard to know what to ask, and on the rare occasion that I knew what to ask, I often didn't know how to ask it.

 

A "variable" is just a name that we can use to access "things".
A "type" is a way of describing what the "thing" actually is: What data it has and what actions it can do.

 

For example:

int a = 0;  // a is a variable of type int with value 0.

List<int> myList = new List<int>(); // myList is a variable of type List<int>

 

18 minutes ago, kaddle said:

square commas

Also

• [ ] are square brackets
• { } are curly braces
• < > are angle brackets
• • Are also called less/greater than or open/close tag, depending on context.
  • <> are also known as guillemets, but that is not common knowledge.

 

[Franck]

Aaaaaand later you will figure out that string is actually a char array.

 

Long story short, it might be confusing at first but you will get it eventually.

 

The simple answer to what an array is would be "It is something that represent a collection of things"

[Guest]

An array is “advanced” because it can store multiple values. 

 

int

byte

char 

all store a single value. 

 

However arrays, lists & strings are a collection of values that can be accessed by an index. 

 

The index indicates the place of the data you’re asking for. 

 

Strings are an array of characters. 

[Mira Yurizaki]

4 hours ago, kaddle said:

so essentially i'm wondering why arrays would be mentioned as being advanced data type along with strings and lists.

It's "advanced" in that it represents something more than a primitive value. Basically, if the data type is not representing a single number or character, it's an "advanced" data type.

 

3 hours ago, kaddle said:

it says that an array is an advanced data type, but in the part about arrays it says the square commas indicate that the variable is an array instead of a normal variable. so i'm confused about how it can be a data type and also be a variable at the same time. so maybe i'm just confused because i'm still new to C#? it sort of makes sense in the context that a variable is an instance of a data type, as someone explained above. yet at the same time a variable itself is a storage container, while the data type is the type of data being stored.

I'm going to assume you're confused by something like this:

int[] foobar = new int[5]

foobar[0] = 12345;

someFunc(foobar)

The second statement is writing a value to some index in the array, which you have an idea of. The third statement however, is using foobar as-is without the square brackets which doesn't make sense when you were told this is an array and so you must use it like the second statement.

 

To explain this, there's an important distinction as to what a variable can hold. A variable can either hold an actual value, or it can hold a reference. A reference is basically a memory location and going to that memory location holds the actual value. While this sounds kind of wasteful (why spend two chunks of memory representing a single thing?), it's actually pretty powerful.

 

If you'd like to have a British professor explain the concept to you (note this is explaining things using C, but it's similar enough):

 

But otherwise, what foobar represents is not a value, but a memory address to a chunk of memory that contains the five values in the array, with foobar itself containing the the address where the first element of the array is. This is something that C# hides from you because if you don't manipulate references correctly, you can royally screw up the program.