C#•7mo ago

Recursion, help finding the base case?

private void btnRepeat_Click(object sender, EventArgs e)
{
    

}

string Repeat(char c, int n)
{
    return string.Empty;

}

private void btnRepeat_Click(object sender, EventArgs e)
{
    

}

string Repeat(char c, int n)
{
    return string.Empty;

}

I think the idea is that if c is 1 letter, it is the base case and then after it increases. Not sure exactly how to implement it, very new to coding

44 Replies

Angius•7mo ago

Do it with a loop, first

ArrayOP•7mo ago

for (int i = 0; i < n; i++) { string Result = Repeat(c,n); } I think something like this

Angius•7mo ago

No, not really This is mixing recursion with loops Just use a loop

ArrayOP•7mo ago

string.Empty = Result for (int i = 0; i < n; i++) { Result += C; } return Result; ?

Angius•7mo ago

Almost

ArrayOP•7mo ago

😦 whats the error

Angius•7mo ago

string.Empty = Result

ArrayOP•7mo ago

Hmm I'm a bit lost

Angius•7mo ago

type name = value Not value = name

ArrayOP•7mo ago

Result = string.Empty ?

Angius•7mo ago

Assuming Result variable already exists If not, it's missing a type

ArrayOP•7mo ago

What do you mean by type?

Angius•7mo ago

The type of the variable C# is a statically and strongly-typed language Everything has a type It could be an int, or a bool, or a DateTime or a Person

ArrayOP•7mo ago

Result can be a string then right?

Angius•7mo ago

Sure

ArrayOP•7mo ago

Now we have to look at recursion I have to practice because I am a bit lost with that

Angius•7mo ago

You seem to be lost with C# in general So, yeah, true

ArrayOP•7mo ago

Yeah 😭 It's rough out here

Angius•7mo ago

Well, the general gist of recursion, is that it's a method that calls itself and uses its own return value

ArrayOP•7mo ago

Yeah My teacher did an example with factorial that helped me Bascially when it was 0 or 1 it was the special case to where it stored those values on the stack for cases so it could trace back to it So like factorial 2 would use the base case of factorial 1 times 2 then 3 would take from prior

Angius•7mo ago

Yep So, adding to string should be even easier Each iteration of the method would simply return a string one longer Until a desired lenght is reached Then the method will not recurse

ArrayOP•7mo ago

Yeah

 private void btnFact_Click(object sender, EventArgs e)
        {
            long n = long.Parse(txtNumber.Text);
            long Result = Factorial(n);

            MessageBox.Show(n + "!= " + Result);

        }

        private long Factorial(long n)
        {
            //base case
            if (n == 1)
                return 1;
            else
            {
                //recursive case
                return n * Factorial(n - 1);
            }


        }

 private void btnFact_Click(object sender, EventArgs e)
        {
            long n = long.Parse(txtNumber.Text);
            long Result = Factorial(n);

            MessageBox.Show(n + "!= " + Result);

        }

        private long Factorial(long n)
        {
            //base case
            if (n == 1)
                return 1;
            else
            {
                //recursive case
                return n * Factorial(n - 1);
            }


        }

@ZZZZZZZZZZZZZZZZZZZZZZZZZ Here is how my teacher did it So we had a base case of 1

Angius•7mo ago

Yeah Adapting it to a string should be easy, then a base of an empty string And instead of multiplying, you'd be adding

ArrayOP•7mo ago

I'm a bit confused on how to format the if statement thoug I said earlier the base case is like if you have 1 letter it is the base case if not you increase

Angius•7mo ago

Yeah, that

ArrayOP•7mo ago

im just a bit confused on how to implement the return

Angius•7mo ago

if (theString.Length < n) Or > n Or whichever else works

ArrayOP•7mo ago

Wouldn't it be = ? == 1

Angius•7mo ago

If you want to check exact equality, sure Probably not 1 though

ArrayOP•7mo ago

Actually I don't even fully understand the base case Hmmm

Angius•7mo ago

Well, you need to start with something

ArrayOP•7mo ago

I was thinking if it was 1 character but really I don't know what it would return - like for factorial I know that if you do factorial 1 or 0 it is just 1 and then AFTER you can extend off that I guess if you have 1 character you can always draw back to that?

Angius•7mo ago

You can have zero characters That's what string.Empty is Or an empty string like ""

ArrayOP•7mo ago

I guess that could maybe be a basecase too should i make 2 if statements?

Angius•7mo ago

Why?

ArrayOP•7mo ago

for the two base cases, if they have 0 or 1 character

Angius•7mo ago

Why would there be two? You start with an empty string Then you keep adding to it Until its length reaches a desired length One base — empty string One check — string reached the desired length

ArrayOP•7mo ago

So if n == 0; I will return an string.empty string?

Angius•7mo ago

Yeah

ArrayOP•7mo ago

Okay

string Repeat(char c, int n)
{
    //base case - if there are no characters, return an empty string (zero)
    if (n == 0)
    {
        return string.Empty;
    }

}

string Repeat(char c, int n)
{
    //base case - if there are no characters, return an empty string (zero)
    if (n == 0)
    {
        return string.Empty;
    }

}

I hav this dowm, is it okay? @ZZZZZZZZZZZZZZZZZZZZZZZZZ now i do an e;se statement saying return c + Repeat(c + 1) ?

Angius•7mo ago

Yep

ArrayOP•7mo ago

wow I am actually choked shocked thank you i cant believe i kinda got one

Core•7mo ago

The else statement is redundant, because if n != 0 it will simply execute the code after the if (n == 0) statement

ArrayOP•7mo ago

this was the correct ans, got it wrong

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Recursion, help finding the base case?