what is the difference between a++ and ++a? they are integer, thought.

Answer 1

Quoting an old post about 'Increment ++ and Decrement -- Operator as Prefix and Postfix'

In programming (Java, C, C++, PHP etc. ), increment ++ operator increases the value of a variable by 1 and decrement -- operator decreases the value of a variable by 1.

Suppose, a = 5 then,
++a; //a becomes 6
a++; //a becomes 7
--a; //a becomes 6
a--; //a becomes 5

Simple enough till now. However, there is a slight but important difference you should know when these two operators are used as prefix and postfix.

++ and -- operator as prefix and postfix

Suppose you use ++ operator as prefix like: ++var. The value of var is incremented by 1 then, it returns the value.

Suppose you use ++ operator as postfix like: var++. The original value of var is returned first then, var is incremented by 1.

e.g

Suppose a = 5,

System.out.println(a++);
// outputs 5
// but after printing, value stored in a is now 6
System.out.println(a);
// outputs 6
System.out.println(++a);
//outputs 7

Answer 2

this question has been posted a hundred times. use the search functionality in the Q&A section, you'll end up with a ton of useful information