Yes, that helps. Thanks. I see now how n goes from 1 to 2 to 3...etc. Now not so sure how i = 1 when the for loop starts.
Yes - I finally caught that part about n as it's just moving in reverse so it gets decremented. Now I'm not sure about i. In the debugger when the program gets to the for loop both n and i are equal to 1. The n I understand but i?
I see. I guess my understanding was that the recursion was over after the recursive call, but it's actually for all the code in draw().
Thanks. I did see that. I have a general understanding of how recursion works I think where the function calls itself again and again but I don't get why the code (for loop) below the draw(n - 1) is recursive.
Right. I was aware it was recursion as stated in the title of my post. I had two questions specific to where the for loop returns after printing #.
Why does the for loop return when it hits the end of the function? Isn't the recursive portion already completed in draw(n - 1)? The rest of it is just normal non-recursive code if I understand it correctly.
It's supposed to be a pyramid but not my code. It's an example of a recursive function from a CS50 lecture and I'm just trying to understand how the code works line by line.
I used the debugger to examine this code but not understanding a couple areas.
- Why does the for loop repeat after it exits to print a new line? If it exits the loop, shouldn't it be done with it?
- Why is n incremented and not i as stated with i++? ```void draw(int n);
int main(void) { int height = get_int("Height: ");
draw(height); }
void draw(int n) { if (n <= 0) { return; }
draw(n - 1);
for (int i = 0; i < n; i++) { printf("#"); } printf("\n"); }
Ah ha! Yes, I did check the docs but I think I just glanced over that portion. Be more careful next time. Now that I took another look at the other ctype.h functions, they all return 1 or 0. I think I confused equivalent python built-in functions as those evaluated to true/false. The < is a less than sign but it seems it doesn't render correctly on Lemmy.
Sorry. It's in C. Updated post. Yes those are titles. I just included the relevant portions rather than the entire code.
This is in C language. When I call rotate() in main, the function returns false for isalpha() even though the string entered for plaintext uses alphabetic characters. Perhaps it's identifying an alphabetic character by its ASCII value ('A' = 65)? I tried to test that out and used (char) with the letter variable in rotate() but it didn't change anything.
PORTION OF MAIN ``` string plaintext = get_string("plaintext: ");
int length = strlen(plaintext); char ciphertext[length];
for (int i = 0; i < length; i++) { ciphertext[i] = rotate(plaintext[i], key); } ```
ROTATE FUNCTION
char rotate(char letter, int key) { if (isalpha(letter) == true) { ...
Ah I see. I had a bad habit of using else if statements instead of else statements because I thought else if could be better in seeing the condition it's testing for so it was clearer. I get the logic is actually different now.
In VS I am told this function "does not return a value in all control paths." A bot told me specifically the issue is with this line: else if (letter + key <= 90). It said that if the outcome results in letter + key equally exactly 90 then a value is not returned, but I thought that was covered where '<=' means 'less than or equals.'
``` char rotate(char letter, int key) { if (isalpha(letter) == true) { if (letter + key > 90) { int overage = letter + key - 90; letter = 64 + overage;
while (letter > 90) { overage = letter - 90; letter += overage; }
return letter; }
else if (letter + key <= 90) { letter += key; return letter; } }
else if (isalpha(letter) == false) { return letter; } ```
What is %.2f? Why is it not just %f? Is there some additional calculation happening? The half function already does all the calculations including splitting the bill, so I'm not sure what %.2f is. (Btw why is this code not formatting correctly in lemmy?)
```// Calculate your half of a restaurant bill
#include #include
float half(float bill, float tax, int tip);
int main(void) { float bill_amount = get_float("Bill before tax and tip: "); float tax_percent = get_float("Sale Tax Percent: "); int tip_percent = get_int("Tip percent: ");
printf("You will owe $%.2f each!\n", half(bill_amount, tax_percent, tip_percent)); }
// TODO: Complete the function float half(float bill, float tax, int tip) { bill += (bill * (tax / 100.0)); bill += (bill * (tip / 100.0));
bill /= 2;
return bill; } ```