If a= 20 then a+=a + + + a; comes out to be 60.... how???

Question

please explain

Answer 1

wow... C++ is amazing!

Answer 2

Because of the way you have spaced out your additions, the compiler is reading it as:

a += a + a; Which is just:

a = a + (a + a); Which is 60.

If you was to space out your additions differently, of course you'll get different answers:

a += a++ + a; or

a = a + a++ + a;

This will leave a with a value of 62, because it's first adding a to a++, which gives 40, and increments to 41. It then increments a by 1, making a 21. Then adds a to 21, forming 62.

a += a + ++a; or

a = a + a + ++a;

This will leave a with a value of 63, because it will first increment a by 1, making it 21. Then it will simply do a + a + a, forming 63.

Answer 3

actually I got the correct answer...
the compiler first reads it.. then executes as + and + is + then again + and + is +.. so 60

if I had written a+= a - - - a.. then the compiler would have done - and - is + then + and - is - so.. he would just subtract it... answer would be 20.

if I had written a+= a + - + - + - a. then he would execute it as + and - is -,,,, then - and + is - ,,,,then - and - is +,,,, then + and + is +,,,, then + and - is -... therefore answer would be 20........

Just a space....

Answer 4

Thanks Cohen.. I was wondering why 60 is coming as the answer

Answer 5

I see. Thank you, that makes sense :) The first part of my answer I was taking a wild guess, as I hadn't seen anything like it before. The other parts still stand true. You learn something new everyday I guess😁