incrementing 'i' ??

[sonir shah]

class TestClass 
{
   public static void main(String args[]) 
   {
      boolean b = false;
      int i = 1;
      do 
      {
         i++ ;
      } while (b = !b);
      System.out.println( i );
   }
}

Answer : It will print 3
According to me, it will print 2 because in a do-while loop the condition is executed atleast once.
Please let me know where am I wrong
Sonir

[Arathi Rajashekar]

Originally posted by sonir shah:

class TestClass 
{
   public static void main(String args[]) 
   {
      boolean b = false;
      int i = 1;
      do 
      {
         i++ ;
      } while (b = !b);
      System.out.println( i );
   }
}

Answer : It will print 3
According to me, it will print 2 because in a do-while loop the condition is executed atleast once.
Please let me know where am I wrong
Sonir

Hi Sonir,
I think you are bit confused her. Do loop executes the statements in loop atleast once, even if while condition is false. In the above program, when do executes the i will be incremented to 2, next while condition is checked, because it is true, the loop continues, at this time the i will be incremented to 3. After this the while statement will be false. And loop end there. results in answer 3

[Valentin Crettaz]

during the first execution of the loop i is incremented (i=2 now) and the condition evaluates to true so we go for another round. During the second execution i is incremented again (i=3 now) and the condition evaluates to false, so the loop is over...
i=3 at the end...

[mark stone]

this one is really really tricky.
the condition while (b = !b);
it looks like b = true at first. and atleast i thought that this one is an infinite loop. just escaped my mind that b is changing as well at each assignment in each loop.
sonir, you have got some great questions. where are you getting such questions from ?

Originally posted by Valentin Crettaz:
during the first execution of the loop i is incremented (i=2 now) and the condition evaluates to true so we go for another round. During the second execution i is incremented again (i=3 now) and the condition evaluates to false, so the loop is over...
i=3 at the end...

[Rob Ross]

The "==" and "=" have cause more programming bugs than many countries on Earth have money.
I remember that Pascal had a colon-equals operator that forced a distinction:
"=" test for equality
":=" assignment.
Since one of the main goals of java was to simplify the language so you avoided common bugs, I'm really really surprised and dissapointed that they didn't adopt two distinct symbols like "==" and ":="; Maybe someday I'll be able to add my own macros to java source code and define these symbols myself ;p
Rob
[ January 17, 2002: Message edited by: Rob Ross ]

[Roy Ben Ami]

actually rob if u think about it, they did simplify it a bit more than c++.
at least a boolean expression is only now true or false, unlike c++ and basic where 0 is false and 1 is true also.
this prevents many such errors as you said!
like:
if (x==5) and
if (x=5)
java will give compile error, and c++ and basic not!