For Loop Iteration Expression

[Finner Jones]

Hi,

Consider these two for loops:

 
for(int i=0; i<2;[B]++i[/B]) {
   System.out.println(i + " in ++loop");
}
 
for(int i=0; i<2;[B]i++[/B]) {
   System.out.println(i + " in loop++");
}
 

When I run this, the output is the same from both:

0 in ++loop
1 in ++loop
0 in loop++
1 in loop++

The iteration part of the for loop is evaluated after the body has been executed. So my question is this:

Does having ++i or i++, in the iteration of a for loop, make a difference to the execution of the body ?


Thanks in advance
Finner
[ July 04, 2006: Message edited by: Finner Jones ]

[wise owen]

In your case ("for(int i=0; i<2; ++i)" and "for(int i=0; i<2; i++)"), they are the same.
[ July 04, 2006: Message edited by: wise owen ]

[Keith Lynn]

No. But you will notice a difference if you use the expressions as part of the condition of the loop.

[James Chegwidden]

Keith is correct remember when used as part of an expression- the side effects take place...

[susan waters]

Even if I use S.O.P in the expression then also no difference

class testing{
public static void main(String args[]){

for(int i=0;i<3;i++,System.out.println(i))
System.out.println("i value in Loop" + i);

for(int j=0;j<3;++j,System.out.println(j))
System.out.println("j value in loop" + j);
}

}

Both display same values any idea ???

[Keith Lynn]

Susan, if you place the expressions in the condition, you will notice a difference. Consider the following.

class Testing{
 
   public static void main(String args[]){
      for(int i=0;i++<3 ;) 
         System.out.println("i value in Loop" + i);
 
      for(int j=0;++j<3 ;) 
         System.out.println("j value in loop" + j);
   }
 
}

[ July 04, 2006: Message edited by: Keith Lynn ]

[James Chegwidden]

In Keith's example the side effects take place..