Static variable question

[Bob Vel]

Friends,
Following example's answer is 5 and 6.
public class StaticDemo
{
static int i = 5;
static
{
System.out.println("Static code: i = "+ i++ );
}
public static void main(String arg[])
{
System.out.println("main: i = "+ i++);
}
}
I thought the answer should be 6 and 6.
Please explain.
Thanks in advance.

[Lam Thai]

Originally posted by Bob Vel:
Friends,
Following example's answer is 5 and 6.
public class StaticDemo
{
static int i = 5;
static
{
System.out.println("Static code: i = "+ i++ );
}
public static void main(String arg[])
{
System.out.println("main: i = "+ i++);
}
}
I thought the answer should be 6 and 6.
Please explain.
Thanks in advance.

Hi Bob,
The result shows that the post-increment operator (++ right after x) does it's job. What post-increment operator does is that it evaluates the associate expression with the current value of x first. Save the answer. Increment the variable. Then move the saving answer into the result's position.
In your case, two calls to System.out.println("..." + x++) will then yield 5 and 6 since:

The first call will just save the value of 5. Incerement x to 6. Send the value of 5 for answer.
The 2nd call will save the value of 6. Increment x to 7. Send the value of 6 for final answer.
I hope that helps....
Regards,
Lam

[Priya Chetlur]

The postfix operator when applied like i++, first uses the current value of i as the value of the expression first and then adds 1 to i. Here it first uses the value 5 to print then increases its value to 6. Similarly in the main.
To make it more clear you can add two more print statements in your code like this:
public class StaticDemo
{
static int i = 5;
static
{
System.out.println("Static code: i = "+ i++ );
System.out.println("After increment in static code i="+i);
}
public static void main(String arg[])
{
System.out.println("main: i = "+ i++);
System.out.println("After increment in main i="+i);
}
}
The output is:
Static code: i=5
After increment in static code i=6
main: i=6
After increment in main i=7
Hope this makes it clear