On Line 9, Why must there be an integer division of current_row and 3? Can anyone elaborate on this concept please?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; }
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.
Notice that this is not a perfectly stepped printout, as dictated by the logic.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...
Also remember that integer division truncates the result, which is why "currentRow/3" produces zero when "currentRow" is 0, 1, and 2.
Last edited by Matticus; 12-06-2012 at 09:39 PM.
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.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
You could also note that the number of stars to be printed on each row, equals the current row number + 1.
