CODEWITHSUNDEEP
carrayspointers
va.
va.

Reputation: 780

C arrays and pointers

Just started to learn C language. I have a pointer array int *parr and I need to fill it with random numbers and then do some other things with it. But I even don't understand how to fill it with random numbers. I tried something like this, but it hangs the program:

for(i=0 ; i<R ; i++)
{
  for(j=0 ; j<C; j++)
    {
    *(parr+i*C+j)=rand() % 10;
    printf("%d",*(parr+i*C+j));
    }
  printf("\n");
}

Upvotes: 0

Views: 257

Answers (2)

fvu
fvu

Reputation: 32953

int *parr;

just defines a pointer to a n integer, but there's no storage associated with it. You could either 

int parr[sizeofarray];

or

int *parr = calloc (sizeofarray, sizeof(int));

to obtain the right amount of storage.

based on your example sizeofarray should be at least R * C.

Upvotes: 2

cnicutar
cnicutar

Reputation: 182609

The way you initialize it, you probably have to malloc memory like this:

parr = malloc(R * C * sizeof(*parr));

Upvotes: 5

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