C#•2y ago

❔ Fix sized array/list

I'm quite new to C#, evidently, and I'm trying to initialise a list (or an array) in a class that shall be defined when an instance of this class is made. Something like:

class Testing {
    Private int[] _cords = new int[2];

    Public Testing(int num1, int num2) {
        _cords = {num1, num2};
    }
}

class Testing {
    Private int[] _cords = new int[2];

    Public Testing(int num1, int num2) {
        _cords = {num1, num2};
    }
}

this code is ofcourse wrong, but I believe it should kinda explain what im trying to do.

20 Replies

Rotaerk•2y ago

so when you do:

class Foo
{
    T fieldName = initialValue;
}

class Foo
{
    T fieldName = initialValue;
}

when the code is compiled, that initialization is actually put into the constructor ... so that's basically the same as:

class Foo
{
    T fieldName;
    public Foo()
    {
        fieldName = initialValue;
    }
}

class Foo
{
    T fieldName;
    public Foo()
    {
        fieldName = initialValue;
    }
}

performing this transformation on your code, you essentially have this:

class Testing
{
    int[] _cords;
    public Testing(int num1, int num2)
    {
        _cords = new int[2];
        _cords = {num1, num2};
    }
}

class Testing
{
    int[] _cords;
    public Testing(int num1, int num2)
    {
        _cords = new int[2];
        _cords = {num1, num2};
    }
}

so the first problem here is that you're initializing the thing twice it's redundant ... only the second one will be kept, and the first is a waste of time second, the syntax itself is wrong in the second case

ACiDCA7•2y ago

well the first problem is actually that access modifiers shouldnt be pascalcase^^

Rotaerk•2y ago

you can do new int[] { num1, num2 } lol yeah I just silently fixed that I haven't used C# version higher than 7, so not sure what syntaxes they've added...

ACiDCA7•2y ago

for the other points i fully agree what you are saying ;)

Rotaerk•2y ago

but I think the most concise way to initialize that would be _cords = new [] { num1, num2 }; unless there's something newer

ACiDCA7•2y ago

 _cords = new[] {num1, num2};

 _cords = new[] {num1, num2};

should work in newer versions i thought in your example there would still be an int in there but after rereading you already omited it... then ignore what i wrote

SolwayFirthOP•2y ago

okay okay thank you goodpeople ✌️

Rotaerk•2y ago

the explicit way is new int[2] { num1, num2 } but the above syntax omits the type and size because they can be inferred also, if these are coordinates, then maybe you should add a second o to the name of your field 😛

SolwayFirthOP•2y ago

whoops

Anton•2y ago

do you want an inline buffer or a heap allocated one? because you can technically do any

SolwayFirthOP•2y ago

i just want to use the least amount of memory that i can

Aaron•2y ago

even just = { num1, num2 } works

MODiX•2y ago

Windows10CE#8553

REPL Result: Success

int[] a = { 1, 2, 3 };
a

int[] a = { 1, 2, 3 };
a

Result: int[]

[
  1,
  2,
  3
]

[
  1,
  2,
  3
]

Compile: 411.493ms | Execution: 66.299ms | React with ❌ to remove this embed.

Anton•2y ago

the least possible would be fixed-size arrays, but you need unsafe code for those there's the unsafe keyword for types and the fixed keyword for arrays

Aaron•2y ago

uh? no you don't if you want to use little memory here, that's easy

MODiX•2y ago

Windows10CE#8553

REPL Result: Success

class Testing
{
    private (int x, int y) _cords;

    public Testing(int num1, int num2)
    {
        _cords = (num1, num2);
    }
}

class Testing
{
    private (int x, int y) _cords;

    public Testing(int num1, int num2)
    {
        _cords = (num1, num2);
    }
}

Compile: 527.634ms | Execution: 42.235ms | React with ❌ to remove this embed.

Anton•2y ago

yeah this too, but this one's not an array not that it matters though

SolwayFirthOP•2y ago

okay thats what im gonna implement

Anton•2y ago

if you had 10 items, a tuple would be less viable

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Fix sized array/list