C#•3mo ago

How do I add strings to a list?

So what I basically want to do is something along the lines of: Title.Add(Console.ReadLine()); I want to save string values and then display them in the program if the user chooses to option. My problem lies in that I have no idea on how this works. I've looked at the MSDN and YouTube videos but I just can't seem to grasp it. Also, I've built up a menu using switch and cases. The biggest problem of them all is that I have yet to find a good explanation on the difference between List<string[]> Title = new List<string[]>(); and List<string> Title = new List<string>(); Since this is assignment, I don't want the answer, I just want to understand how to actually use them and the difference...

98 Replies

SinFluxx•3mo ago

the difference between the two is the same as the difference between string and string[]

Angius•3mo ago

List<string[]> is a list of arrays of strings List<string> is a list of strings

[
    ["abc", "def"],
    ["ghi", "jkl"],
]

[
    ["abc", "def"],
    ["ghi", "jkl"],
]

["abc", "def", "ghi"]

["abc", "def", "ghi"]

oke•3mo ago

the way i think of it is a string[] is an array, and a List<string> is a string[] with more overhead (not correct at all, but might help with a rough visualization)

Angius•3mo ago

You're right, not correct. True that a list has more overhead than an array, but it also has more functionality. It's dynamically-sized for once So it's not like it's overhead for no reason

oke•3mo ago

im just trying not to overwhelm them with a full background of a ~~linked~~ list

Angius•3mo ago

List<T> is not a linked list

oke•3mo ago

wait, theres a type for that nm

Angius•3mo ago

So, @Blane, does that answer your question?

Blane•3mo ago

Hmm. I think I understand a little better. So the List<string[]> is like a bucket full of lists consisting of strings? While List<string> is just a singular list of string? (Sorry for the late response. Had to go grab food.)

oke•3mo ago

yes ["abc", "def", "ghi"] can be assigned to both a string[] and a List<string> but not a List<string[]>

Blane•3mo ago

But is it possible to assign ["abc", "def", "ghi"] to a list, name that list and then assign the list to a List<string[]>?

SinFluxx•3mo ago

You couldn't do that, no, because an array (string[]) is not the same as a List<string>

Blane•3mo ago

So this assignment I'm working on wants me to make a program similar to a blog, where I first type in a title and then the post/description. I'm not sure how to go about this however since I barely knew anything about the difference between lists and lists[] huh... Hmm

oke•3mo ago

// Works
List<string> strList = ["abc", "def", "ghi"];

// Wont work
string[] strArray = strList;

// Will work
string[] strArray = strList.ToArray();

// Works
List<string> strList = ["abc", "def", "ghi"];

// Wont work
string[] strArray = strList;

// Will work
string[] strArray = strList.ToArray();

SinFluxx•3mo ago

Why do you need lists if you're just providing a title and a post/description?

Angius•3mo ago

That seems like a case for classes, not lists or arrays

oke•3mo ago

i think he meant the variable name

Angius•3mo ago

class Blogpost
{
    public string Title { get; set; }
    public string Body { get; set; }
    public DateTimeOffset CreatedAt { get; set; }
}

class Blogpost
{
    public string Title { get; set; }
    public string Body { get; set; }
    public DateTimeOffset CreatedAt { get; set; }
}

Blane•3mo ago

I'm sorry if I can't describe it properly...

Angius•3mo ago

Then you could have a List<Blogpost> you can .Add() more blogposts to

oke•3mo ago

do you mean the name you give the variable? or an actual property?

Blane•3mo ago

Let me read through it again real quick

Angius•3mo ago

Unless we're doing the good ol' "we won't learn classes yet, so use arrays as a a stand-in for objects" with a blogpost being a string[] where [0] is the title and [1] is the body

Blane•3mo ago

I'll use google translate to help me out "The blog should be a list that can save string vectors"

oke•3mo ago

oh, so it is List<string[]> woops

Blane•3mo ago

Every individual blogpost should be a string vector and they should contain at least two elements

Angius•3mo ago

Oof, so I was correct, then

oke•3mo ago

kudos

Blane•3mo ago

He added in bold text beneath: "NOTE: You may not replace the vector list with a class"

Angius•3mo ago

So, it seems like you would have a List<string[]> that is the blog, and each individual string[] would be a blogpost

oke•3mo ago

so your situation would look like:

[
    ["abc", "def"], // Can only have 2
    ["ghi", "jkl"],
    // More list elements
]

[
    ["abc", "def"], // Can only have 2
    ["ghi", "jkl"],
    // More list elements
]

as ZZZZZZZZZZZZ said

Angius•3mo ago

Yeah

oke•3mo ago

ya know, im just gonna make this more difficult ill leave this for Z bye

Blane•3mo ago

I appreciate you taking the time to help me!

Angius•3mo ago

Or, more aptly,

[
    [ "Title", "Lorem Ipsum Dolor Sit Amet" ],
    [ "Hamburger", "Hamburgers are the new superfood according to the scientists" ]
]

[
    [ "Title", "Lorem Ipsum Dolor Sit Amet" ],
    [ "Hamburger", "Hamburgers are the new superfood according to the scientists" ]
]

So, you'd have your

var blog = new List<string[]>();

var blog = new List<string[]>();

and you would be adding blogposts to it with

var post = new[]{ "Title", "Body" };
blog.Add(post);

var post = new[]{ "Title", "Body" };
blog.Add(post);

oke•3mo ago

i think you just gave the answer to their assignment...

Angius•3mo ago

I'm not sure how I could've obfuscated this answer lol

oke•3mo ago

touche lol

Blane•3mo ago

So var blog = new List<string[]>(); is to make the bucket which I will add the blog post to?

Angius•3mo ago

A bucket of buckets Yes

Blane•3mo ago

Hmmmm.... I think I'm starting to understand this now but there are some gaps

Angius•3mo ago

Yeah, it doesn't make much sense to treat each blogpost as a bucket of strings rather than an object with properties But that's what the requirements are Let's maybe distinguish them. Each post on the blog is a bag of strings And the blog is a bucket of those bags

Blane•3mo ago

So the blog in this case is both the Title + Post? Doesn't help that english isn't my first language

Angius•3mo ago

Yes, the blogpost is a bag that contains the title and the post

Blane•3mo ago

Waaaait.... Hold on

Blane•3mo ago

Blane•3mo ago

The second var post = new[]{ "Title", "Body" }; blog.Add(post); What is the reason for the [] next to new?

Angius•3mo ago

To indicate it's an array

oke•3mo ago

its shorthand the full version is:

new string[]

new string[]

it makes writing code faster

Angius•3mo ago

But since both elements are strings, the compiler can figure out that it's strings we want to have there So we don't need to specify it explicitly

Blane•3mo ago

Aaah... So if I were to write it, I would type it out like string post = new string[] {"Title", "Body"};

oke•3mo ago

yup

Blane•3mo ago

hmm okay Then it makes more sense Let me think real quick string blog = new List<string[]>(); string post = new string[]{ "Title", "Body" }; blog.Add(post);

oke•3mo ago

this is also dependant of which language version youre using. if youre using .net Framework (not .net Core) then you have to manually change the language version so using new[] (or new()) would throw an error

Angius•3mo ago

This would work, yes

Blane•3mo ago

I honestly don't remember which one I'm using

oke•3mo ago

string blog = new List<string[]>(); would throw an error because youre assinging a List<string[]> to a string

Angius•3mo ago

No Yeah

string post = new string[]{ "Title", "Body" };

string post = new string[]{ "Title", "Body" };

would not work As oke said

oke•3mo ago

thats a separate issue, so still valid

Angius•3mo ago

Neither would

string blog = new List<string[]>();

string blog = new List<string[]>();

oke•3mo ago

string myString = "This is text";

string[] myStringVector = new string[] { "This is element one", "Element two" };

List<string> myStringList = new List<string>() { "This is element one", "Element two" };

List<string[]> myStringListVector = new List<string[]>() 
{ 
  { "Title", "Body" },
  { "Title", "Body" }
};

string myString = "This is text";

string[] myStringVector = new string[] { "This is element one", "Element two" };

List<string> myStringList = new List<string>() { "This is element one", "Element two" };

List<string[]> myStringListVector = new List<string[]>() 
{ 
  { "Title", "Body" },
  { "Title", "Body" }
};

Blane•3mo ago

hmm

Blane•3mo ago

So to make sure I get it... This is where I create the "bucket" or where I will give the myStringList its title?

Blane•3mo ago

I think what messes me up is the {} afterwards... Also, I feel really dumb and sorry for taking up so much of your time I'm very slow

oke•3mo ago

using {} instead of [] is dependant on how you set the variable im going to use the long version ({}) in case youre using a different language version

Blane•3mo ago

So when I have used lists before, we use [0], [1], [2] and [i] and so on.

oke•3mo ago

this is a constant length, and will always be that assortment of values until its changed what you want is this datatype:

List<string[]>

List<string[]>

Angius•3mo ago

You can

var arr = new string[2];
arr[0] = "foo";
arr[1] = "bar";

var arr = new string[2];
arr[0] = "foo";
arr[1] = "bar";

is equivalent to

var arr = new[]{ "foo", "bar" };

var arr = new[]{ "foo", "bar" };

oke•3mo ago

List<string[]> myBlogs = new List<string[]>()
{
  { // accessed by 'myBlogs[0]'
      "Title", // accessed by 'myBlogs[0][0]'
      "Blog"   // accessed by 'myBlogs[0][1]'
  },
  { // accessed by 'myBlogs[1]'
      "Title", // accessed by 'myBlogs[1][0]'
      "Blog"   // accessed by 'myBlogs[1][1]'
  },
}

List<string[]> myBlogs = new List<string[]>()
{
  { // accessed by 'myBlogs[0]'
      "Title", // accessed by 'myBlogs[0][0]'
      "Blog"   // accessed by 'myBlogs[0][1]'
  },
  { // accessed by 'myBlogs[1]'
      "Title", // accessed by 'myBlogs[1][0]'
      "Blog"   // accessed by 'myBlogs[1][1]'
  },
}

Angius•3mo ago

Let's maybe skip some of the syntax sugar

List<string[]> myBlogs = new List<string[]>()
{
  new string[] { // accessed by 'myBlogs[0]'
      "Title", // accessed by 'myBlogs[0][0]'
      "Blog"   // accessed by 'myBlogs[0][1]'
  },
  new string[] { // accessed by 'myBlogs[1]'
      "Title", // accessed by 'myBlogs[1][0]'
      "Blog"   // accessed by 'myBlogs[1][1]'
  },
}

List<string[]> myBlogs = new List<string[]>()
{
  new string[] { // accessed by 'myBlogs[0]'
      "Title", // accessed by 'myBlogs[0][0]'
      "Blog"   // accessed by 'myBlogs[0][1]'
  },
  new string[] { // accessed by 'myBlogs[1]'
      "Title", // accessed by 'myBlogs[1][0]'
      "Blog"   // accessed by 'myBlogs[1][1]'
  },
}

oke•3mo ago

oh, forgot to do that with the inner parts too lol

Angius•3mo ago

It's equivalent to

List<string[]> myBlogs = new List<string[]>();

myBlogs.Add(new string[] { // accessed by 'myBlogs[0]'
      "Title", // accessed by 'myBlogs[0][0]'
      "Blog"   // accessed by 'myBlogs[0][1]'
  });

myBlogs.Add(new string[] { // accessed by 'myBlogs[1]'
      "Title", // accessed by 'myBlogs[1][0]'
      "Blog"   // accessed by 'myBlogs[1][1]'
  });

List<string[]> myBlogs = new List<string[]>();

myBlogs.Add(new string[] { // accessed by 'myBlogs[0]'
      "Title", // accessed by 'myBlogs[0][0]'
      "Blog"   // accessed by 'myBlogs[0][1]'
  });

myBlogs.Add(new string[] { // accessed by 'myBlogs[1]'
      "Title", // accessed by 'myBlogs[1][0]'
      "Blog"   // accessed by 'myBlogs[1][1]'
  });

Blane•3mo ago

I think I can make it work if I figure out how to register what the user types as the title and blog. The question is how I do that. I've tried with Console.ReadLine(); but I can't get that to work.

oke•3mo ago

Console.ReadLine() prompts the user for text in the console you have to type text, then press enter for the application to get the string

Blane•3mo ago

oooh wait. I accidentally used the vector list instead of the normal one

Angius•3mo ago

There's no "vector" in C#, by the way Just so you know

Blane•3mo ago

okay... so

Angius•3mo ago

List<T> is a list T[] is an array

Blane•3mo ago

Language barrier

oke•3mo ago

based on the description, List<string[]> was the right one

Blane•3mo ago

You know what. I'll just send you a screenshot

oke•3mo ago

i was under the impression C#s List<> == C++s vector<>

Blane•3mo ago

It's the case 2:

Angius•3mo ago

Yes, but it is not called a vector

oke•3mo ago

ohh, okay

Angius•3mo ago

You should create the blogpost array first Then add that array to the list of blogposts

oke•3mo ago

i dont think we'll be able to explain this properly without inadvertently answering your assignment for you

Angius•3mo ago

Yeah

Blane•3mo ago

Hmm...That's true okay. Let's see. I now know (at least I think I do) what the difference between the <string[]> and <string> is

Angius•3mo ago

1. Make an array of strings of length 2 2. Read user input into the [0]th element for the title 3. Read user input into the [1]st element for the body 4. Add the array to the list string[] is an array of strings string is string

Blane•3mo ago

Okay. That makes sense

Angius•3mo ago

List<string[]> is a list of arrays of strings List<string> is a list of strings

oke•3mo ago

List<string> liknar en shoppinglista där du skriver en vara per rad. Exempel: - Mjölk - Bröd - Ägg - List<string[]> liknar en inköpslista där du grupperar varor i kategorier. Varje kategori kan innehålla flera underposter. Exempel: * Mjölkprodukter: - Mjölk - Fil * Bröd: - Rågbröd - Vetebröd - Använder du List<string> så kan du enkelt lägga till eller ta bort varor på listan. List<string[]> används om du vill ha en mer strukturerad lista med underkategorier.

Blane•3mo ago

aaaaaaah

oke•3mo ago

List<string> - Enkel inköpslista Denna kod visar hur man använder en List<string> för att skapa en enkel inköpslista:

// Skapa en lista för inköpsvaror
List<string> inköpslista = new List<string>();

// Lägg till varor i listan
inköpslista.Add("Mjölk");
inköpslista.Add("Bröd");
inköpslista.Add("Ägg");

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string vara in inköpslista)
{
  Console.WriteLine(vara);
}

// Skapa en lista för inköpsvaror
List<string> inköpslista = new List<string>();

// Lägg till varor i listan
inköpslista.Add("Mjölk");
inköpslista.Add("Bröd");
inköpslista.Add("Ägg");

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string vara in inköpslista)
{
  Console.WriteLine(vara);
}

I detta exempel skapas en lista inköpslista av typen List<string>. Sedan läggs olika varor till listan med metoden Add(). Slutligen loopar vi igenom listan med en foreach-loop och skriver ut varje vara. List<string[]> - Grupperad inköpslista med kategorier Denna kod visar hur man använder List<string[]> för att skapa en inköpslista med kategorier:

// Skapa en lista för kategorier med varor
List<string[]> inköpslista = new List<string[]>();

// Lägg till en kategori med varor
inköpslista.Add(new string[] { "Mjölk", "Fil" });
inköpslista.Add(new string[] { "Rågbröd", "Vetebröd" });

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string[] kategori in inköpslista)
{
  Console.WriteLine($" - {kategori[0]}:");  // Skriv ut kategorinamn
  foreach (string vara in kategori)
  {
    Console.WriteLine($"   * {vara}");  // Skriv ut varje vara
  }
}

// Skapa en lista för kategorier med varor
List<string[]> inköpslista = new List<string[]>();

// Lägg till en kategori med varor
inköpslista.Add(new string[] { "Mjölk", "Fil" });
inköpslista.Add(new string[] { "Rågbröd", "Vetebröd" });

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string[] kategori in inköpslista)
{
  Console.WriteLine($" - {kategori[0]}:");  // Skriv ut kategorinamn
  foreach (string vara in kategori)
  {
    Console.WriteLine($"   * {vara}");  // Skriv ut varje vara
  }
}

Här skapas en lista inköpslista av typen List<string[]>. Varje element i listan är en egen array med strängar, som representerar en kategori med tillhörande varor. Vi lägger till kategorier med hjälp av Add() och en ny array med varunamn. När vi loopar igenom listan går vi först igenom varje kategori (kategori), sedan skriver vi ut kategorinamnet. Inuti den loopen går vi igenom varje vara (vara) i kategorin och skriver ut den.

MODiX•3mo ago

oke

REPL Result: Success

List<string> inköpslista = new List<string>();

// Lägg till varor i listan
inköpslista.Add("Mjölk");
inköpslista.Add("Bröd");
inköpslista.Add("Ägg");

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string vara in inköpslista)
{
  Console.WriteLine(vara);
}

List<string> inköpslista = new List<string>();

// Lägg till varor i listan
inköpslista.Add("Mjölk");
inköpslista.Add("Bröd");
inköpslista.Add("Ägg");

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string vara in inköpslista)
{
  Console.WriteLine(vara);
}

Console Output

Inköpslista:
Mjölk
Bröd
Ägg

Inköpslista:
Mjölk
Bröd
Ägg

Compile: 482.941ms | Execution: 41.809ms | React with ❌ to remove this embed.

MODiX•3mo ago

oke

REPL Result: Success

List<string[]> inköpslista = new List<string[]>();

// Lägg till en kategori med varor
inköpslista.Add(new string[] { "Mjölk", "Fil" });
inköpslista.Add(new string[] { "Rågbröd", "Vetebröd" });

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string[] kategori in inköpslista)
{
  Console.WriteLine($" - {kategori[0]}:");  // Skriv ut kategorinamn
  foreach (string vara in kategori)
  {
    Console.WriteLine($"   * {vara}");  // Skriv ut varje vara
  }
}

List<string[]> inköpslista = new List<string[]>();

// Lägg till en kategori med varor
inköpslista.Add(new string[] { "Mjölk", "Fil" });
inköpslista.Add(new string[] { "Rågbröd", "Vetebröd" });

// Skriv ut innehållet i listan
Console.WriteLine("Inköpslista:");
foreach (string[] kategori in inköpslista)
{
  Console.WriteLine($" - {kategori[0]}:");  // Skriv ut kategorinamn
  foreach (string vara in kategori)
  {
    Console.WriteLine($"   * {vara}");  // Skriv ut varje vara
  }
}

Console Output

Inköpslista:
 - Mjölk:
   * Mjölk
   * Fil
 - Rågbröd:
   * Rågbröd
   * Vetebröd

Inköpslista:
 - Mjölk:
   * Mjölk
   * Fil
 - Rågbröd:
   * Rågbröd
   * Vetebröd

Compile: 467.845ms | Execution: 51.133ms | React with ❌ to remove this embed.

Blane•3mo ago

Thank you guys so much for the help. Was finally able to understand it now after some sleep. I really appreciate you guys taking the time out of your day to help me. The Swedish explanation helped a lot!

Gaming

Programming

How do I add strings to a list?