Increment or a variable
x++;  // increment x by one and returns the old value of x
++x;  // increment x by one and returns the new value of x

x an integer or long (possibly unsigned) The original or newly incremented value of the variable.
x = 2;
y = ++x;      // x now contains 3, y contains 3

x = 2;
y = x++;      // x now contains 3, while y still contains 2