Looking for a little help please...

Hello everyone,

I am currently taking CS50x thru Edx.org and was hoping someone would be kind enough to help explain something to me. Please keep in mind I have had zero experience in programming. My first weeks project was to write a code that would ask the user to input a number between 0 and 23 and then the code would build a half pyramid to the height the user stated starting with to hashes at the top.
Example: for 8 it would show
..............##
............###
..........####
........#####
......######
....#######
..########
#########
Except without the .'s. I couldn't get my spaces to stay put.
I did finally get it to work but getting the hashes to print was totally trial and error. Under //Print hash, I originally though h should equal 2 because I wanted to start with 2 hash marks but instead it was giving me 2 additional lines above my pyramid. So I started playing with that number just to see what would happen and got it to work with h = 0. I was hoping someone would be able to tell me why this is the case. I just need to understand why it works so I can learn from it. I hope I gave enough info. Thanks in advance.

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Code:

---

#include <cs50.h>
#include <stdio.h>


int main(void)
{
    // Declare variable for pyramid height
    int height;
   
    //Prompt user to enter pyramid height and make sure it is within the range
    do
    {
        printf("Please enter a number between 0 and 23: ");
        height = GetInt();
    }
    while (height < 0 || height > 23);
   
    //Print pyramid
    for (int i = 1; i <= height; i++)
    {
   
        //Print space
        for (int s = height - i; s > 0; s--)
        {
            printf(" ");
        }
       
        //Print hash
        for (int h = 0; h <= i; h++)
        {
            printf("#");
        }
       
        //Print new line
        printf("\n");
       
    }
       
}

---

Within your outer "Print pyramid" loop, you are printing the data for one line at a time (and ending with a "\n"). So your "Print hash" loop has to print all the #'s that are going to appear on one line. Now, if you want (say) two hashes on the first line, you have to make sure the inner loop will run twice during the first iteration of the outer loop. The outer loop's control variable i starts at 1 and goes up. So if the inner loop starts from 0 and goes <= i, this will be in the range [0,1] or 0-1 for the first line, meaning you'll print two hashes.

Basically, it's worth thinking about the loops inductively. Figure out what happens in the first iteration, then make sure the loop variables are going in the right direction (getting larger or smaller) and assume induction will take care of the other loop iterations. Then all you have to do is make sure the loop executes the right number of times; perhaps think through the last loop iteration to make sure it seems correct. Think in terms of hypotheticals: suppose i is 1, then what happens in the inner loops? And so on.

Thanks for the reply dwks. I appreciate the input. I hope this all becomes clearer to me soon. This is only my first week so I cannot get discouraged.