C#•3y ago

✅ Advent of Code Day 1 - Issue with Chars

For this problem, you essentially have to find the first and last digit contained in each line, so for a line

271lonepxp2flbmbz

271lonepxp2flbmbz

the first digit would be

and the last digit

as well. Put 'em together, you get

. Now you have to find that value for each of the 1000 lines provided and add them all together.

string input = """
9sixsevenz3
seven1cvdvnhpgthfhfljmnq
6tvxlgrsevenjvbxbfqrsk4seven
9zml
""";

int sum = 0;
foreach(string word in input.Split())
{
    List<int> nums = [];
    foreach(char ch in word)
    {
        if(Char.IsDigit(ch))
        {
            nums.Add(Convert.ToInt32(ch - '0'));
        }
    }

    int firstNumber = nums[0];
    int lastNumber = nums[^1];
    int fullNumber = firstNumber * 10 + lastNumber;
    sum += fullNumber;
}

Console.WriteLine(sum);

string input = """
9sixsevenz3
seven1cvdvnhpgthfhfljmnq
6tvxlgrsevenjvbxbfqrsk4seven
9zml
""";

int sum = 0;
foreach(string word in input.Split())
{
    List<int> nums = [];
    foreach(char ch in word)
    {
        if(Char.IsDigit(ch))
        {
            nums.Add(Convert.ToInt32(ch - '0'));
        }
    }

    int firstNumber = nums[0];
    int lastNumber = nums[^1];
    int fullNumber = firstNumber * 10 + lastNumber;
    sum += fullNumber;
}

Console.WriteLine(sum);

This is my code. However, I just keep getting an

Index Out of Range

Index Out of Range

error on the line that says

int firstNumber = nums[0];

int firstNumber = nums[0];

and I just don't get why. I originally had the code a lot more condensed but I expanded it to debug and that appears to be where the issue is. Naturally I initially thought that nothing was being added to the array, but so far I can't figure out why that would be. I'm going to go and

Console.WriteLine

Console.WriteLine

nums

nums

right now to see if it actually contains anything, but either way I'd appreciate it if someone could help me see what I did wrong here.

AdiZOP•12/3/23, 1:35 PM

Please ping me if you reply, thanks!

AdiZOP•12/3/23, 1:44 PM

Yeah,

nums

nums

does appear to have numbers being added to it, so it just doesn't make sense to me.

MODiX•12/3/23, 1:44 PM

AdiZ

REPL Result: Failure

string input = """
9sixsevenz3
seven1cvdvnhpgthfhfljmnq
6tvxlgrsevenjvbxbfqrsk4seven
9zml
""";

int sum = 0;
foreach(string word in input.Split())
{
    List<int> nums = [];
    foreach(char ch in word)
    {
        if(Char.IsDigit(ch))
        {
            nums.Add(Convert.ToInt32(ch - '0'));
        }
    }

    int firstNumber = nums[0];
    int lastNumber = nums[^1];
    int fullNumber = firstNumber * 10 + lastNumber;
    sum += fullNumber;
}

Console.WriteLine(sum);

string input = """
9sixsevenz3
seven1cvdvnhpgthfhfljmnq
6tvxlgrsevenjvbxbfqrsk4seven
9zml
""";

int sum = 0;
foreach(string word in input.Split())
{
    List<int> nums = [];
    foreach(char ch in word)
    {
        if(Char.IsDigit(ch))
        {
            nums.Add(Convert.ToInt32(ch - '0'));
        }
    }

    int firstNumber = nums[0];
    int lastNumber = nums[^1];
    int fullNumber = firstNumber * 10 + lastNumber;
    sum += fullNumber;
}

Console.WriteLine(sum);

Exception: CompilationErrorException

Compile: 608.932ms | Execution: 0.000ms | React with ❌ to remove this embed.

MODiX•12/3/23, 1:45 PM

AdiZ

REPL Result: Failure

Exception: CompilationErrorException

Compile: 445.149ms | Execution: 0.000ms | React with ❌ to remove this embed.

AdiZOP•12/3/23, 1:45 PM

Ohhhh

AdiZOP•12/3/23, 1:50 PM

But why? That should work?

AdiZOP•12/3/23, 1:51 PM

Running this:

Prints and but then fails on trying to print the in the second line.

AdiZOP•12/3/23, 1:52 PM

I'm so confused.

Joschi•12/3/23, 2:33 PM

Right at the start of your loop.
Insert a Console.WriteLine(word) and take a look what it outputs

AAdiZ But why? That should work?

TheRanger•12/3/23, 2:33 PM

bot is still on .net 7

JJoschi Right at the start of your loop. Insert a Console.WriteLine(word) and take a loo...

AdiZOP•12/3/23, 2:34 PM

Not at the PC right now, but I remember running a for each loop that literally just printed the word and that worked fine

TTheRanger bot is still on .net 7

AdiZOP•12/3/23, 2:35 PM

Good to know, thanks.

AAdiZ Not at the PC right now, but I remember running a for each loop that literally j...

Joschi•12/3/23, 2:46 PM

Huh ok yeah, I actually did not know that String.Split defaults to a new line as delimiter.

But your code works on my end

Joschi•12/3/23, 2:47 PM

Returns

TheRanger•12/3/23, 2:53 PM

sounds right to me

AdiZOP•12/3/23, 4:32 PM

That's so irritating

AdiZOP•12/3/23, 4:32 PM

It just fails on my PC. Other code works fine though... When I get back I'll try again and let you know. Thanks @Joschi!

AdiZOP•12/3/23, 7:17 PM

@Joschi something definitely isn't working here

AdiZOP•12/3/23, 7:18 PM

https://pastebin.com/WJAv27nB

Pastebin

using System.Diagnostics.Tracing;string input = """9sixsevenz3seven...

Pastebin.com is the number one paste tool since 2002. Pastebin is a website where you can store text online for a set period of time.

AdiZOP•12/3/23, 7:18 PM

This is my code (sorry it's so long, I just want the entire thing there in case something's wrong with it

AdiZOP•12/3/23, 7:18 PM

And after executing the loop on the first word, I get this error:

AdiZOP•12/3/23, 7:19 PM

And VS is telling me that the error happens on line

AdiZOP•12/3/23, 7:19 PM

Which is this:

AdiZOP•12/3/23, 7:20 PM

If you could test that entire code for me and let me know if it's still working on your machine and not mine that'd be great

AdiZOP•12/3/23, 7:20 PM

Because I just don't get it

Joschi•12/3/23, 7:20 PM

Which string does he parse while it crashes?

Joschi•12/3/23, 7:20 PM

Maybe there are strings that do not contain numbers

AdiZOP•12/3/23, 7:20 PM

The only conversion happening is on chars that have already been deemed to contain a digit

AdiZOP•12/3/23, 7:21 PM

And would fail then, not the line that is failing right now.

AdiZOP•12/3/23, 7:21 PM

Right?

Joschi•12/3/23, 7:22 PM

Your code assumes that there is at least one element in

nums

nums

.
If your input doesn't contain any numbers on some line, it will crash

Joschi•12/3/23, 7:22 PM

If you try a test like you should see it crash

AdiZOP•12/3/23, 7:23 PM

Then I don't think it would fail on the second line...

AdiZOP•12/3/23, 7:23 PM

Wait two secs

MODiX•12/3/23, 7:23 PM

AdiZ

REPL Result: Success

Console Output

Compile: 505.699ms | Execution: 34.891ms | React with ❌ to remove this embed.

AdiZOP•12/3/23, 7:23 PM

AdiZOP•12/3/23, 7:24 PM

I thought that might have been the issue

AdiZOP•12/3/23, 7:24 PM

A list of one element.

AAdiZ Which is this: ```cs int firstNumber = nums[0]; ```

Joschi•12/3/23, 7:24 PM

this line will crash if your list does not contain any elements

AAdiZ And after executing the loop on the first word, I get this error: ``` System.Arg...

Joschi•12/3/23, 7:24 PM

with this exact error

AdiZOP•12/3/23, 7:26 PM

Aha

AdiZOP•12/3/23, 7:26 PM

Changed it to this

AdiZOP•12/3/23, 7:26 PM

And it ran fine!

AdiZOP•12/3/23, 7:26 PM

And it was correct! Amazing.

AdiZOP•12/3/23, 7:27 PM

I just don't get why it was crashing on the second word, which so clearly had numbers in it.

AdiZOP•12/3/23, 7:27 PM

Come to think of it, when I was debugging, it said that

nums

nums

was

null

null

, how did I not realize what that meant

AAdiZ Come to think of it, when I was debugging, it said that `nums` was `null`, how d...

Joschi•12/3/23, 7:28 PM

That should not be possible with your code, but well if it works it works

AdiZOP•12/3/23, 7:28 PM

I won't fix what's not broken

AdiZOP•12/3/23, 7:28 PM

Onto part two - thank you for all the help and quick responses!

string input = """ 9sixsevenz3 seven1cvdvnhpgthfhfljmnq 6tvxlgrsevenjvbxbfqrsk4seven 9zml """; int sum = 0; foreach(string word in input.Split()) { List<int> nums = []; foreach(char ch in word) { if(Char.IsDigit(ch)) { nums.Add(Convert.ToInt32(ch - '0')); } } int firstNumber = nums[0]; int lastNumber = nums[^1]; int fullNumber = firstNumber * 10 + lastNumber; sum += fullNumber; } Console.WriteLine(sum);