C#•7mo 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 the first digit would be 2 and the last digit 2 as well. Put 'em together, you get 22. 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 error on the line that says 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 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.

24 Replies

AdiZ•7mo ago

Please ping me if you reply, thanks! Yeah, nums does appear to have numbers being added to it, so it just doesn't make sense to me.

MODiX•7mo ago

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

- Invalid expression term '['
- Syntax error; value expected

- Invalid expression term '['
- Syntax error; value expected

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

MODiX•7mo ago

AdiZ

REPL Result: Failure

List<int> lst = [1,2,3]; Console.WriteLine(lst[2]);

List<int> lst = [1,2,3]; Console.WriteLine(lst[2]);

Exception: CompilationErrorException

- Invalid expression term '['

- Invalid expression term '['

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

AdiZ•7mo ago

Ohhhh But why? That should work? Running this:

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

int sum = 0;
foreach(string word in input.Split())
{
    List<int> nums = new();
    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;

    foreach(int num in nums)
    {
        Console.WriteLine(num);
    }
}

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

int sum = 0;
foreach(string word in input.Split())
{
    List<int> nums = new();
    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;

    foreach(int num in nums)
    {
        Console.WriteLine(num);
    }
}

Prints 9 and 3 but then fails on trying to print the 1 in the second line. I'm so confused.

Joschi•7mo ago

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

TheRanger•7mo ago

bot is still on .net 7

AdiZ•7mo ago

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

Joschi•7mo ago

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

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

int sum = 0;
foreach(string word in input.Split())
{
    Console.WriteLine("The Word is: " + word);
    List<int> nums = new();
    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("The Nums are:");
    foreach(int num in nums)
    {
        Console.WriteLine(num);
    }
}

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

int sum = 0;
foreach(string word in input.Split())
{
    Console.WriteLine("The Word is: " + word);
    List<int> nums = new();
    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("The Nums are:");
    foreach(int num in nums)
    {
        Console.WriteLine(num);
    }
}

Returns

The Word is: 9sixsevenz3
The Nums are:
9
3
The Word is: seven1cvdvnhpgthfhfljmnq
The Nums are:
1
The Word is: 6tvxlgrsevenjvbxbfqrsk4seven
The Nums are:
6
4
The Word is: 9zml
The Nums are:
9

The Word is: 9sixsevenz3
The Nums are:
9
3
The Word is: seven1cvdvnhpgthfhfljmnq
The Nums are:
1
The Word is: 6tvxlgrsevenjvbxbfqrsk4seven
The Nums are:
6
4
The Word is: 9zml
The Nums are:
9

TheRanger•7mo ago

sounds right to me

AdiZ•7mo ago

That's so irritating 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! @Joschi something definitely isn't working here

AdiZ•7mo ago

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.

AdiZ•7mo ago

This is my code (sorry it's so long, I just want the entire thing there in case something's wrong with it And after executing the loop on the first word, I get this error:

System.ArgumentOutOfRangeException: 'Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')'

System.ArgumentOutOfRangeException: 'Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')'

And VS is telling me that the error happens on line 1018 Which is this:

int firstNumber = nums[0];

int firstNumber = nums[0];

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 Because I just don't get it

Joschi•7mo ago

Which string does he parse while it crashes? Maybe there are strings that do not contain numbers

AdiZ•7mo ago

The only conversion happening is on chars that have already been deemed to contain a digit And Convert.ToInt32() would fail then, not the line that is failing right now. Right?

Joschi•7mo ago

Your code assumes that there is at least one element in nums. If your input doesn't contain any numbers on some line, it will crash If you try a test like input = "hello" you should see it crash

AdiZ•7mo ago

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

MODiX•7mo ago

AdiZ

REPL Result: Success

List<int> list = new() {1};
Console.WriteLine(list[0]);
Console.WriteLine(list[^1]);

List<int> list = new() {1};
Console.WriteLine(list[0]);
Console.WriteLine(list[^1]);

Console Output

1
1

1
1

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

AdiZ•7mo ago

Oh I thought that might have been the issue A list of one element.

Joschi•7mo ago

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

AdiZ•7mo ago

Aha

if(nums.Count == 0)
{
    continue;
}
int firstNumber = nums[0];
int lastNumber = nums[^1];
int fullNumber = firstNumber * 10 + lastNumber;
sum += fullNumber;

if(nums.Count == 0)
{
    continue;
}
int firstNumber = nums[0];
int lastNumber = nums[^1];
int fullNumber = firstNumber * 10 + lastNumber;
sum += fullNumber;

Changed it to this And it ran fine! And it was correct! Amazing. I just don't get why it was crashing on the second word, which so clearly had numbers in it. Come to think of it, when I was debugging, it said that nums was null, how did I not realize what that meant 🤦

Joschi•7mo ago

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

AdiZ•7mo ago

I won't fix what's not broken 😂 Onto part two - thank you for all the help and quick responses!

Joschi•7mo ago

Good luck with the second part!

AdiZ•7mo ago

Thanks 🙂

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✅ Advent of Code Day 1 - Issue with Chars