Increment Operator

[Alpana Singh]

I came across this question.

public class static1{
public static void main (String args[])
{
int i=0;
i=i++;
i=i++;
i=i++;
System.out.println(i);
}
}

And the ouput generated is 0.I can't understand why?
Please help.

[Tim McGuire]

The ++ is evaluated after the assignment.

so i starts out as zero.
i=i++; // assign the value of i as zero, then increment. The incremented value is not kept!

i is still zero for the next expression:
i=i++; // same as saying i=0

and so on

try it with i = ++i instead to see the difference.

[Srinivasa Raghavan]

Also have a look at these simple one
good one

[Steve Morrow]

The ++ is evaluated after the assignment.

Not quite; the assignment happens *last*. The increment occurs after the expression "i++" is evaluated. That expression ("i++") evaluates to the original value of i, and the result is "remembered". If the result of the expression "i++" is stored back into i, it's as if nothing happened at all. Here's another example:

int i = 0;
i = i++ + i++;

The right-hand expression is evaluated as follows, starting with the first i++, the second i++, then adding the results of those two expressions, then assigning *that* value to i...

1. i++    // The value of this expression evaluates to the current
          // value of i, but increments i afterward. So, this expression
          // is 0 (remember that), but i is then incremented to 1.
 
   i = 0(1) + i++; 
 
2. i++    // See number 1. But this time, the expression evaluates to 
          // 1 (remember this, too), but then i is incremented to 2. We'll
          // see that this last increment is irrelevant to the process.
 
   i = 0 + 1(2); 
          
3. 0 + 1  // Now, the results of the two expressions are added together. If
          // you remember, the first expression evaluates to 0, and the 
          // second expression evaluates to 1.
 
   i = 0 + 1;
          
4. i = 1  // The result of the binary expression (a + b) is then assigned
          // the i variable. So, i is now equal to 1.

[ September 30, 2005: Message edited by: Steve Morrow ]

[Alpana Singh]

Thanks Steve,Tim and Raghavan for clearing this.