basic pointer question need help

I'm trying to work with a dynamically sized "array" of a structure called atoms. I declare an atom pointer like so:

atom *atoms;

Then, I allocated memory for a bunch of atom structures like so:

atoms = (atom *)malloc(100*sizeof(atom));

Then, I loop from 1 to 100 trying to set values in each atom structure from one to 100 by using commands such as:

atoms[i].atom_name = atom_name_variable;
atoms[i].atom_type = atom_type_variable;

However, when I break out of this for loop, and using Microsofts Visual C++ debugger, I only have one atom object, the first one I processed and not 100 like I should have. What am I doing wrong here?

>I loop from 1 to 100

Loop from 0 to 99.

Sorry, I do loop from 0 to 99, but I don't know why I don't seem to get a list of 100 atom objects, unless Visual C++'s debugger is not showing me things properly.

I don't see a problem in the code you are posting; I would guess that your problem is in the code that you aren't posting. Is there some minimal bit you could post that would give this its necessary context?

• What is atom_name? An array of char? A pointer? An int?
• What is atom_type?
• Where and how are you changing i?
• What does the loop look like?
• Are you checking malloc's return value?

Here is an example.

Code:

---

#include <stdio.h>
#include <stdlib.h>

struct sAtom
{
    char name[32];
    char type[16];
};

int main(void)
{
    int i, count = 100;
    struct sAtom *atom = malloc(count * sizeof(*atom));
    if ( atom != NULL )
    {
        for ( i = 0; i < count; ++i )
        {
            sprintf(atom[i].name, "Name%02d", i);
            sprintf(atom[i].type, "Type%02d", i);
            printf("i = %2d, name = \"%s\", type = \"%s\"\n", i,
                  atom[i].name, atom[i].type);
        }
        printf("i = %d\n", i);
        free(atom);
    }
    return 0;
}

---

it's the darn Microsoft Visual C++ debugger. It must have a glitch in how it's displaying variable values, because I was able to manually verify that the values are being populated correctly. Sorry.