What are the purpose of pre/post Increment and decrements operators ?

Question

how they works ?
where can we to use pre and where post ?

Answer 1

To understand Pre-increment and Post-increment note that:

$b=$a++; // post-increment
is equivalent to:
$b=$a;
$a++; //$a=$a+1;

while

$b=++$a; // pre-increment
is equivalent to:
$a++; //$a=$a+1;
$b=$a;

In both cases $a is increment of 1 (respect the original value), while $b is incremented only in pre-increment case.

Pre-increment and Post-increment are both equivalent to the execution of 2 statements ($b=$a; $a++;), what change is the order in which these statements are executed.

I hope this can help.

Answer 2

As the words itself suggest us :
pre means before, we have to use the operator first then variable name like (++a)
In this case first the value of a will increase by one then the new value of a will used.

post means after , we have to use operator after variable name like (a++)
In this case current value of will be in use and value will be increase by one in later steps (in the memory it will increase by one)

suppose,

a=5;
b=++a;
in this case , now the values in memories are a=6,b=6
but if we use
b=a++;
then the values in memories are a=6; but b=5;

Answer 3

They are shorthands for x+=1 and x-=1.
Indeed, they are more useful than the normal ways (+=1 and -=1) because in machine language the increment operation is faster than the add operation

Answer 4

why we increment the value of a?
we have also increase the value of a by factor 1 itself

Answer 5

in pre case

Answer 6

Self answering???????????????????????????????????? I will explain better

Let a=1
Cout<<++a;
Cout<<a;

The output will be 2. 2.

Now
Cout<<a++;
Cout<<a;

The output is. 1. 2.