2 - Explain the working of this code

Question

int a = 8;
for(int a = 4 ; a <8 ; a += 2)
{
cout << --a;

}
output : 3456

Answer 1

Here's an edited version of my previous answer, I will follow Gordon's style for writing the steps, because I see it is much more comprehensible : )

First iteration:
a = 4
--a decrement a -> 3
then outputs 3
a += 2 adds 2 into a
then a becomes 5

Second iteration:
a = 5
--a decrement a -> 4
then outputs 4
a += 2 adds 2 into a
then a becomes 6

Third iteration:
a = 6
--a decrement a -> 5
then outputs 5
a += 2 adds 2 into a
then a becomes 7

Fourth iteration:
a = 7
--a decrement a -> 6
then outputs 6
a += 2 adds 2 into a
then a becomes 8

And finally ...
a = 8

The condition a < 8 no longer satisfies, and the loop ceases repetition.

Thanks to Gordon for an excellent example of a way to describe the steps with better details 👍.

Hth, cmiiw

Answer 2

a = 4, loop while a < 8, increment by 2. Note the prefix decrement operator is being used within the loop.

a = 4 outputs 3, add 2 -> 5,
a = 5 outputs 4, add 2 -> 6
a = 6 outputs 5, add 2 -> 7
a = 7 outputs 6, add 2 -> 8
a = 8, loop terminates ...

Hth, cmiiw

Answer 3

Ipang means output is 3456,

for example
"a = 4 outputs 3, add 2 -> 5"

means

In first iteration,
At beginning a = 4
--a so outputs 3
(without line break)
After first iteration
a+=2 so a becomes 5

You interpret his answer like this please

Answer 4

Gordon Not at all, I have seen inspiring people who gave kind and clear answers before, and didn't give up on explaining, and I think you are one : )

Well it is good then you passed him that lesson link, in that case 👍

Hth -> Hope that helps, and ...
cmiiw -> correct me if I'm wrong ...

I thought everybody knew : )

Answer 5

Saad Mughal Great 👍 and you're welcome : )

Answer 6

https://www.sololearn.com/learn/CPlusPlus/1610/

Read here about the difference between prefix and postfix

And please share your understand here

Answer 7

Saad Mughal Sorry for late reply, just got home. Yes, Gordon explanation is right, I meant to write that way, apologies for unclear explanation. And if it wasn't clear enough please tell, we will try best to assist : )

Answer 8

Ipang wow, you are super kind and super patient to type all these 👏👏👏

I thought he didn't understand the ++/-- he asked another similar question a moment after I answered this question.

By the way, i am very curious
What's
hth, cmiiw?

Answer 9

Oh now I know 😂

Answer 10

Ipang the answer is 3456 not
5678 the a+=2 not working in the output please explain more

Answer 11

Oke

Answer 12

Thanks Ipang i just forget operators no problem now