C#•2y ago

Arrays in constructors and lists

I have made a constructor taking an array of int (int[] numbers) in a new class, let's call the class Digits. I have made a public property to an array of int in the class called num (with get; set;). I then make a new object in my main class and assign some numbers, three of them: Digits tmpobj = new(new int[] { 16,23,51 }); I then try to make a list: List<Digits> myList = new List<Digits>(); myList.Add(tmpobj); If I do a Console.Writeline(tmpobj.num[0]); it will return 16. If I increment it with one I get 23 etc. I then do a foreach (var item in myList). I've done a breakpoint after that and I see that myList in this case shows [0] .num[0] = 16, next 23 etc. Then I've done a Console.Writeline after each item and it's just returning the int32 stuff, I thought the "Add" method would add the full array to the list but it does not. I can see that stuff isn't right but I'm not sure how to fix this at the moment. Please help 😅

13 Replies

ero•2y ago

the Add method doesn't add an array to the list it adds an instance of Digits to the list

Ice_•2y ago

Ooooh. Of course! It's an object. Makes sense. Thanks!

ero•2y ago

if you want, you could override ToString

Ice_•2y ago

I was thinking of that but I really just wanted to try it the hard way 😅 List can be used to add, let's say integers or strings as well. How would I create a list from tmpobj declared at top? Its integers in mind

ero•2y ago

i'm not sure what you mean

Ice_•2y ago

Hm nevermind. I guess foreach is only for lists?

ero•2y ago

foreach is for anything that implements IEnumerable anything that you can... enumerate if you want to enumerate over an instance of Digits, you'd have to have that class implement IEnumerable<int> (presumably)

Ice_•2y ago

Hm okay, that is a bit over my expertise right now 😝 I'm aware IEnumerable is an (interface?) but I don't know much about it. So in my case, foreach isn't exactly ideal to write out the integer array from the class object?

ero•2y ago

it's just not even possible unless you do foreach (int i in tmpobj.num)

Ice_•2y ago

Ah... Thanks a lot! Makes great sense. I think I was confused about list, object and datatypes!

MODiX•2y ago

Ero#1111

REPL Result: Success

Digits dgts = new(42, 123, 1337);

foreach (int i in dgts)
{
Console.WriteLine(i);
}

class Digits : IEnumerable<int>
{
private readonly int[] _nums;

public Digits(params int[] nums)
{
    _nums = nums;
}

public IEnumerator<int> GetEnumerator()
{
    return ((IEnumerable<int>)_nums).GetEnumerator();
}

IEnumerator IEnumerable.GetEnumerator()
{
    return _nums.GetEnumerator();
}
}

Digits dgts = new(42, 123, 1337);

foreach (int i in dgts)
{
Console.WriteLine(i);
}

class Digits : IEnumerable<int>
{
private readonly int[] _nums;

public Digits(params int[] nums)
{
    _nums = nums;
}

public IEnumerator<int> GetEnumerator()
{
    return ((IEnumerable<int>)_nums).GetEnumerator();
}

IEnumerator IEnumerable.GetEnumerator()
{
    return _nums.GetEnumerator();
}
}

Console Output

42
123
1337

42
123
1337

Compile: 664.115ms | Execution: 75.350ms | React with ❌ to remove this embed.

ero•2y ago

love ya modix never fail to disappoint me with the goddamn indentations

Ice_•2y ago

Great post! Impressive bot btw!

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Arrays in constructors and lists