operator precedence

[Meher Parveen]

I have a doubt in operator precedence...
evaluation of

result =5+i++%4*i ;

give a result of 7. It should be 9 since ++ has higher precedence that % or *.

The result of 7 also means 4*i is evaluated before i++ or i++%4?!

I am confused!
-Meher

[Peter Ricke]

3 Things to know:

1) result =5+i++%4*i ;
is equal to
result =5+(((i++)%4)*i) ;
because:
++ and -- goes first
than */ and %
and at last + -

if two operations are equal (like * and %) move from left to right

2)i++ returns the i-value before the increment (here 1)
but after this (left side of i++) i = 2

Summary :
i++%4 == 1 (as i++==1)
i*i ==2 as now i==2
5+2==....
Hope this helps...

[Peter Ricke]

Uppps

one of the last lines went wrong:

i*i ==2 as now i==2

should be 1*i ==2 as now i==2

[Vishwanath Krishnamurthi]

Hi Meher,

Can you please tell the initial value of i here..

[Meher Parveen]

The initial value of i was 1.
Thanks for the detailed explanation Peter. That really helped.
-Meher

[nico dotti]

Great breakdown Peter. Another question related to this example. I, for some reason, can't grasp why 1 % <ANYINT> always comes out as 1. Of course above is an example as 1%4 gives us 1 and then we multiply that times 2 and add to 5 to get 7. But can you explain why 1 % any int returns 1 (I know this is basic but for some reason I just don't get it) thanks

[Bert Bates]

As of the 1.4 exam and later, this type of detail in precedence is NOT on the exam.

Related topics that are still on the exam include:

- short circuit
- pre and postfix precedence
- casting

Can any recent candidates remember any others?

[Vishwanath Krishnamurthi]

Hi nico,

We know % always return the remainder after division

so for 8%5 we do 8/5 and take the remainder as our modulo (we know its 3)

or in other words we do,

5*(some-possible-integer)+rr=8 and take the rr value here as our modulo.here it comes out as 5*(1)+3 and we take rr as the modulo here rr=3


for 5%8 it becomes 5*(some-possible-integer)+rr where rr is the remainder
and that possible integer is 0, so here rr has to be 5.... ie modulo is 5

or putting it otherwise, (smallNo)%(bigNumber)==>(smallNo)

likewise there...

[nico dotti]

Thanks for your answer! Confusion though:

5%8 it becomes 5*(some-possible-integer)+rr where rr is the remainder and that possible integer is 0, so here rr has to be 5.... ie modulo is 5

Did you mean 5%8 becomes 8*(some...). If so I think you've answered and I get it: Since 8*1 would be, well too much because it would be 8 which is over 5, we do 8*0 which leaves remainder of 5. Hence, 5%8=5
Is this right?