C#•2y ago

✅ mistery -foreach cycle executed three times for no apparently reason

Here is the code. I checked more and more times for errors, I always putted some breakpoint in order to see into variables, and I just seeing that when the cycle arrive at the last char contained in input (that's a string), it just rest all index to 0 and start again for a total of 3 executions. Am I committing error somewhere? 🧐

41 Replies

ero•2y ago

that's not possible

uselessxpOP•2y ago

yeah I know, usually stupid errors are committing by beginners in cycle statement, but in this case I'm really going crazy, I'm pretty sure all it's ok

uselessxpOP•2y ago

it's like it re-execute those rows again, out of the cycle 🧐

ero•2y ago

can you show more of your code?

uselessxpOP•2y ago

the only explanation is that the whole function is called more times

ero•2y ago

like where that method is being called?

uselessxpOP•2y ago

I think it's so <:picard_facepalm:616692703685509130>

using System.Collections;
using System.Text;

namespace AOC_2015_1
{
    internal class DayOnePartTwo
    {
        static void Main(string[] args)
        {
            string? input;
            Console.WriteLine("Where should I delivery the next gift?");
            Console.SetIn(new StreamReader(Console.OpenStandardInput(), Encoding.UTF8, false, 8192));
            input = Console.ReadLine();
            if (GiftDelivery(input).Item2 == 1337) Console.WriteLine($"Final floor is {GiftDelivery(input).Item1} and Santa never entered the basement");
            else Console.WriteLine($"Final floor is {GiftDelivery(input).Item1} and the first time when Santa enter the basement is {GiftDelivery(input).Item2}");
        }

        static (short, short) GiftDelivery(string input)
        {
            short floor = 0;
            const char floorUpChar = '(';
            const char floorDownChar = ')';
            short x = 0; //for the cycle
            short y = 0; //for the basement check
            List<short> basement = new();

            foreach (char c in input)
            {
                if (floor == -1)
                {
                    basement.Add(y);
                    Console.WriteLine("asd " + basement[x]);
                    x++;
                }
                if (c == floorUpChar)
                {
                    floor++;
                    y++;
                }
                else if (c == floorDownChar)
                {
                    floor--;
                    y++;
                }
            }

            if (basement.Count == 0) return (floor, 1337);
            else return (floor, basement[0]);
        }
    }
}

using System.Collections;
using System.Text;

namespace AOC_2015_1
{
    internal class DayOnePartTwo
    {
        static void Main(string[] args)
        {
            string? input;
            Console.WriteLine("Where should I delivery the next gift?");
            Console.SetIn(new StreamReader(Console.OpenStandardInput(), Encoding.UTF8, false, 8192));
            input = Console.ReadLine();
            if (GiftDelivery(input).Item2 == 1337) Console.WriteLine($"Final floor is {GiftDelivery(input).Item1} and Santa never entered the basement");
            else Console.WriteLine($"Final floor is {GiftDelivery(input).Item1} and the first time when Santa enter the basement is {GiftDelivery(input).Item2}");
        }

        static (short, short) GiftDelivery(string input)
        {
            short floor = 0;
            const char floorUpChar = '(';
            const char floorDownChar = ')';
            short x = 0; //for the cycle
            short y = 0; //for the basement check
            List<short> basement = new();

            foreach (char c in input)
            {
                if (floor == -1)
                {
                    basement.Add(y);
                    Console.WriteLine("asd " + basement[x]);
                    x++;
                }
                if (c == floorUpChar)
                {
                    floor++;
                    y++;
                }
                else if (c == floorDownChar)
                {
                    floor--;
                    y++;
                }
            }

            if (basement.Count == 0) return (floor, 1337);
            else return (floor, basement[0]);
        }
    }
}

ero•2y ago

you literally call that method 3 times yourself

uselessxpOP•2y ago

damn

ero•2y ago

4 times even Console.SetIn(new StreamReader(Console.OpenStandardInput(), Encoding.UTF8, false, 8192)); is absolutely unnecessary (and a memory leak)

Angius•2y ago

Call it once, save the result in the variable, reference that variable Since you're using an unnamed tuple, you could even use tuple reconstruction to make everything nice and named

var (foo, bar) = GiftDelivery(...);

var (foo, bar) = GiftDelivery(...);

and .Item1 will be in foo and .Item2 will be in bar

uselessxpOP•2y ago

yeah I like this

uselessxpOP•2y ago

one of the first modifies I made to the code consist in this and I didn't want to reverrse it

uselessxpOP•2y ago

is var better than short ?

Angius•2y ago

var is for type inference

uselessxpOP•2y ago

oh ok I have to use it mandatory for avoid calling twice the method

Angius•2y ago

It is short if you assign a short to it

uselessxpOP•2y ago

yeah but I also noticed that

var (item1, item2) = GiftDelivery(input);

var (item1, item2) = GiftDelivery(input);

does not works with short also if I use short everywhere

Angius•2y ago

Wym "doesn't work"?

uselessxpOP•2y ago

what do you think about converting rows like this:

input = Console.ReadLine();
var (item1, item2) = GiftDelivery(input);

input = Console.ReadLine();
var (item1, item2) = GiftDelivery(input);

to this:

var (item1, item2) = GiftDelivery(Console.ReadLine());

var (item1, item2) = GiftDelivery(Console.ReadLine());

could it be a good practice or it's stupid? it doesn't seems to accept it, now I try again

Angius•2y ago

static (short, short) GiftDelivery(string input)

static (short, short) GiftDelivery(string input)

the method has to actually return a tuple

MODiX•2y ago

Angius#1586

REPL Result: Success

(short, short) Foo() {
    return (6, 8);
}

var (a, b) = Foo();
Console.WriteLine($"a is {a} and b is {b}");

(short, short) Foo() {
    return (6, 8);
}

var (a, b) = Foo();
Console.WriteLine($"a is {a} and b is {b}");

Console Output

a is 6 and b is 8

a is 6 and b is 8

Compile: 672.899ms | Execution: 88.116ms | React with ❌ to remove this embed.

uselessxpOP•2y ago

and can't a tuple have a defined type?

uselessxpOP•2y ago

that's what I tried to do

Angius•2y ago

No Because a tuple can contain a string and an int, for example Tuple deconstruction needs var

uselessxpOP•2y ago

ok as I know, in DB a tuple is a row I'm reading that a tuple in C# can contains multiple values, isn't like an array so?

Angius•2y ago

Kinda-sorta Something between an array and an object

uselessxpOP•2y ago

interesting

ero•2y ago

or (short a, short b) = ...

uselessxpOP•2y ago

that's make sense. but I realized I have to use var also if all variables are same type working in this way, but not working if I put short out, doesn't it understand that I want both short maybe

Angius•2y ago

Show the code that doesn't work Because if you're using tuples, tuple deconstruction can't not work

uselessxpOP•2y ago

(short item1, short item2) = GiftDelivery(Console.ReadLine());     //works
var (item1, item2) = GiftDelivery(Console.ReadLine());     //works
short (item1, item2) = GiftDelivery(Console.ReadLine());     //does not works

(short item1, short item2) = GiftDelivery(Console.ReadLine());     //works
var (item1, item2) = GiftDelivery(Console.ReadLine());     //works
short (item1, item2) = GiftDelivery(Console.ReadLine());     //does not works

Angius•2y ago

Well, yeah Because it's not a short It's (short, short)

uselessxpOP•2y ago

that's ok but why at this point not requiring

(var item1, var item2) = GiftDelivery(Console.ReadLine());

(var item1, var item2) = GiftDelivery(Console.ReadLine());

Angius•2y ago

Sure, you can But why (var foo, var bar) if you can var (foo, bar)

uselessxpOP•2y ago

I don't und why the compiler in this case understand that both are var, and it doesn't when I put short

Angius•2y ago

var is not a type var is "go figure out what type it is" It doesn't understand that "both are var"

uselessxpOP•2y ago

ok, but is intended to take the place of a type

Angius•2y ago

It understands that it should figure out the types I guess you could say var is special in this case. If you have (string, int, bool) you can't deconstruct it to a variable of any concrete type You need var (a, b, c) or (string a, int b, bool c) or (var a, var b, var c) Sure, in your case all elements of the tuple are of the same type But handling this special case is just not worth it So the compiler wasn't made to handle it Since if you want explicit types you can do (T1 a, T2 b) and if you want the compiler to figure it out you use var (a ,b)

uselessxpOP•2y ago

wow when I thought to have learned all bases 🤣 I imagine it was an hard work to write this compiler, or a compiler in general

Angius•2y ago

Probably, yeah We have a few people in the server who are on C#'s compiler team, actually Might ask them about it if you're curious, #roslyn sounds like it might be a good place

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✅ mistery -foreach cycle executed three times for no apparently reason