Why the output of this code is 1?

Question

int a = 1;
a = a++;
System.out.println(a);

Answer 1

Not 100% but i think it is because of the way it is being interpretted by the compiler.Which is make a new copy of a then plus 1 to the original a.

so if you say
int a = 1;
a++;
print(a)

it will work as expected

Answer 2

so much efforts Jojo 😮

Answer 3

Yep! Had to think about it though. Prefix 1, i= 1+1

Answer 4

@Jojo explain it well, if you want a more accurate explanation, I'll be glad to give it to you but know where it will go.
Beware beware, I'll try to make you understand some basics of assembly😂

Answer 5

It is because of the order of operator
First we put 1 in a (int a =1)
Secondly we save the value of a to put it in a as ++ is after the variable it increments and not before
Then we increment a
Then we put 1 that was save in a

Answer 6

Yes you're right, that's why i=i++ + ++i; // if i=0, i's value will be 2 and not 3
Dunno if you understand..

Answer 7

Rupendra
a=a++; is a valid expression.

But this is what happen :
(It is the SAME variable, the NUMBERS are here to ILLUSTRATE)

a2=a1++; is like :
a2=a1; // useless but valid
a1++; // increments a1 but a1 doesn't exist anymore ! a1++ increments a value wich has been OVERWRITTEN. So the statement is ignored.

Another exemple : int i=0;
i=i++ + ++i;
is like
i+=1; // i=0+1=1
i=i+i; // i=1+1=2
i+=1; // i=i+1=3? nope...

Let see with the number (used to ILLUSTRATE, i1, i2... are the SAME VARIABLE)
i=i1++ + ++i1;
i2=i1+1; // i1=0, i2=1.
i3=i2+i2; // i3=2.
i2=i1+1; // oops i2 doesn't exist anymore... i2 wich was equal to 1 was OVERWRITTEN by i3 wich equals 2.

I know it's quite very very very difficult to explain and understand (maybe I chose a bad way to explain it) so I won't be angry if you don't understand... 😀

Anyway if you have questions on this answer ask me

Answer 8

You can do it as Jay said:
"int a = 1;
a++;"

or if you want to do it your old way you could try this:
"int a = 1;
a = ++a;"

Please correct me if I'm wrong, but the a++ returns the value of "a" and then increments it, when the ++a, first increments the value and then returns it.

Answer 9

Yeah... I like incrementation, but I feel my head's gonna explose soon

Answer 10

the correct answer is 1 2 3 4 .. to infinit