While reversing the user's inputted string...This code won't work properly.Why?In C programming. Please take time to view code..

Question

I divide this code into two sections....

------------------------------------------------------------------------------------------------------------

First section (OUTPUT-1):

In this section,I tend to reverse the users inputted string....

In this process, i initialise the Reversed string character in (char array) i.e char c[100] one by one...

And after that process,I output that initialised characters one by one
Eg: printf("%c",c[0]);
printf("%c",c[1]);
printf("%c",c[2]);
.... etc

It's output also work very well....

---------------------------------------------------------------------
---------------------------------------------------------------------
Second section (OUTPUT - 2);

In this section,I tend to output that whole reversed string....Which is stored in a char array(i.e char c[100])

Like this

printf("%s",c);

But, while doing this process.I found unexpected output in second section (OUTPUT - 2)

and also OUTPUT - 1 != OUTPUT - 2

https://code.sololearn.com/cTtpn9bz6HLg/?ref=app

Answer 1

int k = 0;
Should be outside of the for(){} loop.

Solved see:
https://code.sololearn.com/c2WpIRCNkSNL/?ref=app

Answer 2

Yup Arsenic said it all.
In the second doubt u are declaring k as static which means it can be initialized only once in the whole program.

On each iteration(loop cycle) it's not reinitialising it's value back to 0. That's why the 2nd cases is working.

Answer 3

Just keep in mind every time loop runs it will set k = 0
That's why it's being reset.

Hope u got it &
You are welcome Yogeshwaran

Answer 4

Yogeshwaran you are initialising *k* back to zero on every iteration of the loop. So everytime it overwriting first value of the reversed string "c".
the fix as mentioned by Aakaanksha 💕 is to put it outside the loop.

Answer 5

For the second doubt. Static variables are only initialised once that's why for the next iterations it is not reinitialising its value back to 0

Answer 6

Thank you so much Aakaanksha 💕 and Arsenic for clearing my doubt....😊

Answer 7

Yogeshwaran that's because " int k = 0 " is a part inside the loop.
So everytime the it loops, this statment also gets executed hence *k* is again set to 0 in the begining of the loop

Answer 8

Indeed, it can't be accessed outside the loop.

Answer 9

Thanks a lot Aakaanksha 💕 😊

Answer 10

Can you tell me why we should include int k = 0.
Outside the for loop?in practical or theoretical way

Aakaanksha 💕 also see this code...
It work well when int k = 0 inside a for loop....
but one exception is, I placed a static keyword before a int k...

please tell, how this change the output entirely

static int k vs int k (Inside for loop)
https://code.sololearn.com/cVOP71Apmsf9/?ref=app

Answer 11

Thank you so much 🙌 Arsenic......
Now I understood....

And also tell me.Is the variable declared inside the for loop has a local scope?

Answer 12

Thank you very Arsenic for yours quick answer🙌🙏😊
and thank you so much Aakaanksha 💕 for yours answers which clear my doubts😊🙏🙌

Answer 13

Aakaanksha 💕 and Arsenic again i have a doubt in my code.........

You said that,int k value inside the for loop is always initialised to Zero.... while running the loop....(due to int k = 0 inside a for loop)

Then how does OUTPUT-1(first section) work properly....
(eg)
if b == 5(length of string)
c[k] = a[b- i] // 4
c[0] = a[3]
c[1] = a[2]
c[2] = a[1]
c[3] = a[0]

here,how does the "k" value initialise to 0,1,2,3....?
please tell me...

https://code.sololearn.com/cTtpn9bz6HLg/?ref=app

Answer 14

Yogeshwaran just have a look at this altered version of your code. (I have just changed the stuf you are printing inside the loop) 👇

https://code.sololearn.com/c1KdjXooRlG6/?ref=app

if you still have doubts then feel free to ask.🙂

Answer 15

Aakaanksha 💕 and Arsenic can you please tell me....
Why for loop reinitialise (reset) the int k value[present inside the for loop]

Is it nature of for loop?

If yes means, please tell me.How it was implemented and what is the use of it?
https://code.sololearn.com/cTtpn9bz6HLg/?ref=app

Answer 16

Thank you so much Arsenic for yours clear explanation via code🙌😊

Answer 17

Regarding static vs non-static in C.

In your example that uses 'static', the initialization is part of the static definition and in fact it is done at *compile time*. A fixed memory address is allocated for k, and initialized with 0. When your compiled code is loaded it is already 0,and has no runtime initialization.
If you have separated it into

static k;
k = 0;

It would also not have worked because k would get written by 0 every loop iteration as in the non-static example.

As a rule of thumb, don't put static declarations inside loops.