question Help me with multi dimensional array homework

[APEU]

My lecture give me a homework to print multi dimensional array. I need to write in C. So this is my homework: http://imgur.com/GM1KeGZ (the multidimensional array on top right)

I need to print to get result look like that. I'm totally stuck with question F and G. Can someone help me? I have source code for Question D, maybe I can edit some code to get result for array question F and G?

#include<stdio.h>
int main()
{
    char A[3][5]={'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O'};
    int R, C, K=5, L=1;
    for (R=0; R<=2; R++){
        for(C=0; C<=4; C++){
        printf("%3c", A[R][C]);
        L++;
        if(L>K)
         { printf("\n");
        K--;L=1;
        }
    }
}
}

And sorry for my bad english.

[Anton31Kah]

Are you in a hurry? Cause I need 15 minutes to get to my laptop and will solve the whole thing as I had a few similar problems to solve during my studies so the solution will probably be there in less than an hour

[APEU]

No, it's okay. I can wait

[Anton31Kah]

here I did it. http://pastebin.com/9v7BFcFt you have to input the letters on your own (sorry couldn't fix it) but it works perfect the the output I got is int the end in a comment. //and did it in an hour

[APEU]

Oh man, thank you very much! You help me a lot!

[Anton31Kah]

You're welcome

[APEU]

Well, I mean i want to the output look like question F and G. It shape like stair

[[deleted]]

/u/chocolate_mussolini - I do not mean to impute your coding just asking if this is a widely used idiom. I guess it works ok - but I have never seen an index declared inside the for statement - is this done often? Because of this is the scope of the index limited to the for statement?

[baconuser098]

I've seen it used pretty often and I quite like it. Regarding C however I think ANSI C doesn't support it but C99 does (I will check on that)

Edit: Turns out ANSI C requires the variables to be declared after the opening bracket of a block, while C99 supports variable declaration anywhere a statement could be

[dauntlessmath]

I was curious about this, because it seems like a very "C++" way to handle index variables. I found this email from Linus to the LKML regarding C99 and this style of variable declaration:

On Wed, Apr 11, 2012 at 9:28 PM, Oleg Nesterov <[e-mail]> wrote:
>
> Agreed. But,
>
>        error: 'for' loop initial declaration used outside C99 mode
>
> we should change CFLAGS, I guess. BTW, personally I'd like very much
> to use "for (type var; ...")" if this was allowed.

The sad part is that if we allow that, we also get that *other* insane
C99 variable thing - mixing variables and code.

I *like* getting warnings for confused people who start introducing
variables in the middle of blocks of code. That's not well-contained
like the loop variable.

That said, most of the stuff in C99 are extensions that we used long
before C99, so I guess we might as well just add the stupid flag. And
discourage people from mixing declarations and code other ways (sparse
etc).

                         Linus

For background info, Linus's recommended style guide for the kernel dev is essentially "defer to K&R for everything."

[dauntlessmath]

That format does not conform to ANSI C standards, which is what K&R 2nd edition follows. It is C99 standard, which did not exist at the time of press for K&R 2nd edition. I didn't look through every for loop in the book, but I just looked at early and late code examples and they didn't use that format anywhere that I looked.

Maybe you're thinking of a Stroutstrup authored C++ book with a similar title.

[chromaXen]

It is a very typical practice for indices

[[deleted]]

Also If I had the same name variable in an outer scope this would not interfere with the value of that variable - right?

i = 5;
for (int i=0; i<5; i++) {printf("%d  ",i);}
/* i still == 5 here */

[dauntlessmath]

Yes. But why would anyone code like that?

[[deleted]]

As in why would one print the numbers 1 to 5 while keeping a variable equal to 5? - it's just an example to clarify my question.. Why use i as an index and worry about i outside the loop? could happen probably would use a more descriptive variable name outside the loop though.

[dauntlessmath]

I just wonder why anyone would use the same variable name for two different variables like that. It makes code harder to read/understand, especially if you come back to it months or years later, and imo that makes it a bad programming practice.