Is there a difference between x++ and ++x in java?

Question

Is there a difference between ++x and x++ in java?

Answer 1

In Java there is a difference between x++ and ++x

++x is a prefix form: It increments the variables expression then uses the new value in the expression.

For example if used in code:

int x = 3;

int y = ++x;
//Using ++x in the above is a two step operation.
//The first operation is to increment x, so x = 1 + 3 = 4
//The second operation is y = x so y = 4

System.out.println(y); //It will print out '4'
System.out.println(x); //It will print out '4'

x++ is a postfix form: The variables value is first used in the expression and then it is incremented after the operation.

For example if used in code:

int x = 3;

int y = x++;
//Using x++ in the above is a two step operation.
//The first operation is y = x so y = 3
//The second operation is to increment x, so x = 1 + 3 = 4

System.out.println(y); //It will print out '3'
System.out.println(x); //It will print out '4' 

Hope this is clear. Running and playing with the above code should help your understanding.

Answer 2

yes

++x increments the value of x and then returns x
x++ returns the value of x and then increments

example:

x=0;
a=++x;
b=x++;

after the code is run both a and b will be 1 but x will be 2.

Answer 3

Yes, using ++X, X+1 will be used in the expression. Using X++, X will be used in the expression and X will only be increased after the expression has been evaluated.

So if X = 9, using ++X, the value 10 will be used, else, the value 9.

Answer 4

Yes, there is a difference, incase of x++(postincrement), value of x will be used in the expression and x will be incremented by 1 after the expression has been evaluated, on the other hand ++x(preincrement), x+1 will be used in the expression. Take an example:

public static void main(String args[])
{
    int i , j , k = 0;
    j = k++; // Value of j is 0
    i = ++j; // Value of i becomes 1
    k = i++; // Value of k is 1
    System.out.println(k);  
}