Java nested loop question

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On this kind of program i understand that if the j>i the program goes to the outer loop, and it increments i so it can go back in but when it goes back in the j is supposed to be at 2 because we incremented it before we got back to the outer loop but as i've seen when we go back in j is at 1 and not 2, i do not understand wh

What I have tried:

Java

import java.util.Scanner;
public class Exercise16 {

   public static void main(String[] args)

{
   int i,j,n;
   System.out.print("Input number of rows : ");
 Scanner in = new Scanner(System.in);
		    n = in.nextInt();

   for(i=1;i<=n;i++)
   {
	for(j=1;j<=i;j++)
	  System.out.print(j);

    System.out.println("");
    }
}
}

Posted 18-Jul-18 10:42am

Member 13917084

Updated 18-Jul-18 11:05am

CPallini

v2

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CPallini · Answer 1 · 2018-07-18T11:05:00

Solution 2

Quote:
but when it goes back in the j is supposed to be at 2 because we incremented it before we got back to the outer loop

Nope. That is a wrong assumption. In fact, j is 1 again, because, at every outer loop iteration, the inner loop initialization part (j=1) is executed.

Posted 18-Jul-18 11:05am

CPallini

Updated 18-Jul-18 11:06am

v2

Patrice T · Answer 2 · 2018-07-18T11:04:00

Quote:
i do not understand wh

Your code do not behave the way you expect, or you don't understand why !
Just watch it preform.

There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.

The downside of this solution:
- It is a DIY, you are the one tracking the problem and finding its roots, which lead to the solution.
The upside of this solution:
- It is also a great learning tool because it show you reality and you can see which expectation match reality.

secondary effects
- Your will be proud of finding bugs yourself.
- Your learning skills will improve.

You should find pretty quickly what is wrong.

Debugger - Wikipedia, the free encyclopedia[^]
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html[^]
https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html[^]
The debugger is here to only show you what your code is doing and your task is to compare with what it should do.