Ternary Operator

[sunetra sen]

Please go through the following code:
public class TerOp{
public static void main(String asd[]){
int x=0;
x=(true) ? x++ : x--;
System.out.println("x= "+x);//1
}
}
It gives the value of x as 0 at line 1.
Can somebody explain why this is so?
Thanks.

[Dan Chisholm]

The statement
x=(true) ? x++ : x--;
can be reduced to
x = x++;
The expression x++ will return the value of x which is zero. Before the assignment operation is complete the value of x is incremented. After the increment operation is complete the previous value of x, which was zero, is assigned to x.
The following code example demonstrates that the value of x is indeed incremented before the expression is completely evaluated.

class A {
  static int m(int i) {
    System.out.print(i + ",");
    return 0;
  }
  public static void main (String[] args) {
    int i = 0;
    i = i++ + m(i);
    System.out.print(i);
  }
}

What is the result of attempting to compile and run the above program? 
a.  Prints: 0,0 
b.  Prints: 1,0 
c.  Prints: 0,1 
d.  Prints: 1,1 
e.  Runtime error 
f.  Compiler error 
g.  None of the above 

The answer is b, "Prints: 1.0".

The statement contains an addition operation. The left operand is a postfix operation and it is evaluated first. The result of the postfix operation is zero, but variable i is incremented as a side effect. The right hand operand of the addition operation is the result of method m. As a side effect, method m prints the current value of variable i which is one. Method m then returns the value zero. The result of the addition operation is zero and that is the value that is assigned to variable i.

[Alfred Kemety]

First <condition>? <expression1> : <expression2>
If condition is true, then expression 1 is evaluated and expression 2 is not.
x++ will use the original value of x (0) and then increment x to be equal (1)
Yet the equality operator (=) will assign the value (0) that came out of the ? : to x after all this happen, so x becomes back 0 after it was incremented to 1
if you change the x++ to ++x it will print 1
HTH

[sunetra sen]

Thanks guys !javascript: x()