Tracing a asterisks triangle program

Code:

---

# include <stdio.h>

void printTriangle(int num_rows)
        {
                int currentRow;
                int currentStar;
                for(currentRow = 0; currentRow < num_rows; currentRow++)
                {
                        for(currentStar = 0; currentStar <= currentRow + (currentRow / 3 ); currentStar++)
                        {
                                printf("*");
                        }

                        printf("\n");
                }
        }

int main()
{
    printTriangle(5);

    return 0;
}

---

On Line 9, Why must there be an integer division of current_row and 3? Can anyone elaborate on this concept please?

Learning to follow a program step by step is a vital skill when you're trying to master the concepts.

Let's look at the inner loop.

Code:

---

/* loop 1 */
currentRow = 0

currentStar <= currentRow + (currentRow / 3 )

This is how many stars you want to print on the first loop.
currentRow + (currentRow / 3 ) = 0 + 0/3 = 0 + 0 = 0
Because of the "<=", you will print one star.

/* loop 2 */
currentRow = 1

currentStar <= currentRow + (currentRow / 3 )

currentRow + (currentRow / 3 ) = 1 + 1/3 = 1 + 0 = 1
Two stars will be printed.

/* loop 3 */
currentRow = 2

currentStar <= currentRow + (currentRow / 3 )

currentRow + (currentRow / 3 ) = 2 + 2/3 = 2 + 0 = 2
Three stars will be printed.

/* loop 4 */
currentRow = 3

currentStar <= currentRow + (currentRow / 3 )

currentRow + (currentRow / 3 ) = 3 + 3/3 = 3 + 1 = 4
Five stars will be printed.

etc...

---

Notice that this is not a perfectly stepped printout, as dictated by the logic.

Also remember that integer division truncates the result, which is why "currentRow/3" produces zero when "currentRow" is 0, 1, and 2.

Matticus strikes again! Thank you!

You're very welcome! And I just correct an error in my post - for the last case, I accidentally had "Four stars will be printed."

> On Line 9, Why must there be an integer division of current_row and 3? Can anyone elaborate on this concept please?
You could
change it to /2, run the code and observe the changes to the output.
change it to /4, run the code and observe the changes to the output.

You could also note that the number of stars to be printed on each row, equals the current row number + 1. ;)