MPI : Wondering about process sequence and for-loops - for-loop

Question

I am trying to build something with MPI, so since i am not very familiar with it, i started with some arrays and printing stuff. I noticed that a plain C command (not an MPI one) works simultaneously on every process, i.e. printing something like that :
printf("Process No.%d",rank);
Them i noticed that the numbers of the processes got all scrambled and because the right sequence of the processes would fit me, i tried using a for-loop like that :
for(rank=0; rank<processes; rank++) printf("Process No.%d",rank);
And that started a third world war in my computer. Lots of strange errors in a strange format that i couldn't understand and that made me suspicious. How is it possible since an if-loop stating a ranks value , like the master rank:
if(rank==0) printf("Process No.%d",rank);
cant use a for-loop for the same reason. Well, that is my first question.
My second question is about an other for-loop i used, that it got ignored.
printf("PROCESS --------------->**%d**\n",id);
for (i = 0; i < PARTS; ++i){
printf("Array No.%d\n", i+1);
for (j = 0; j < MAXWORDS; ++j)
printf("%d, ",0);
printf("\n\n");
}
I run that for-loop and every process printed only the first line:
$ mpiexec -n 6 `pwd`/test
PROCESS --------------->**0**
PROCESS --------------->**1**
PROCESS --------------->**3**
PROCESS --------------->**2**
PROCESS --------------->**4**
PROCESS --------------->**5**
And not the following amount of zeros (there was an array there at first that i removed cause i was trying to figure out why it didn't get printed).
So, why is it about MPI and for-loops that don't get along?
--edit 1: grammar
--edit 2: Code paste
It is not the same as above, but same problem in the the last for-loop with fprintf.
This is a paste zone, sorry for that, i couldn't deal with the code system here
--edit 3: fixed
Well i finally figured it out. For first i have to say that the fprintf function when used inside MPI is a mess. Apparently there is a kind of overlap while every process writes in a text file. I tested it with the printf function and it worked. The second thing i was doing is, i was calling the MPI_Scatter function from inside root:
if(rank==root) MPI_Scatter();
..which only scatters the data inside the process and not the others.
Now that i have fixed those two issues, the program works as it should, apart a minor problem when i printf the my_list arrays. It seems like every array has a random number of inputs, but when i tested using a counter for every array, it's only the data that is printed like this. Tried using fflush(stdout); but it returned me an error.
usr/lib/gcc/x86_64-pc-linux-gnu/4.2.2/../../../../x86_64-pc-linux-gnu/bin/ld: final link failed: `Input/output error collect2: ld returned 1 exit status`

Answer 1

MPI in and of itself does not have a problem with for loops. However, just like with any other software, you should always remember that it will work the way you code it, not the way you intend it. It appears that you are having two distinct issues, both of which are only tangentially related to MPI.
The first issue is that the variable PARTS is defined in such a way that it depends on another variable, procs, which is not initialized at before-hand. This means that the value of PARTS is undefined, and probably ends up causing a divide-by-zero as often as not. PARTS should actually be set after line 44, when procs is initialized.
The second issue is with the loop for(i = 0; i = LISTS; i++) labeled /*Here is the problem*/. First of all, the test condition of the loop always sets i to the value of LISTS, regardless of the initial value of 0 and the increment at the end of the loop. Perhaps it was intended to be i < LISTS? Secondly, LISTS is initialized in a way that depends on PARTS, which depends on procs, before that variable is initialized. As with PARTS, LISTS must be initialized after the statement MPI_Comm_size(MPI_COMM_WORLD, &procs); on line 44.
Please be more careful when you write your loops. Also, make sure that you initialize variables correctly. I highly recommend using print statements (for small programs) or the debugger to make sure your variables are being set to the expected values.