What is a difference between x++ and ++x???

Answer 1

You Mean Prefix and Postfix
The prefix ++x ( rise the value then use it) form first performs the increment operation and then returns the value of the increment operation.
The postfix x++ (use it then rise the value) form first returns the current value of the expression and then performs the increment operation on that value. For example:

int count=1;
System.out.println(++count); >> this displays 2

int count=1;
System.out.println(count++); >> this displays 1

Answer 2

try it in a code like this i dont know c++ but
in java javascirpt
if x is 1
a=++x; // x incroment BEFORE "a" get the value
now a is 2 and x = 2

if x is 1
a=x++; // x incroment AFTER "a" get the value
now a is 1 and x = 2

but try it i cold flip this around