Accessing members of structs in a list in C - c

Question

I have been working through the exercises in K&R on my quest to learn C, and I've hit a strange problem. I wrote a program to count words, characters, and lines in a file, then draw a histogram displaying the count for each. Everything worked well until I tried to make my code a little more reusable with a struct. My struct is as follows:
struct category {
char *name;
int namelen;
int count;
};
and it's values are assigned by a constructor function:
struct category createCat(char *name) {
struct category cat = {name, get_width(name), 0};
return cat;
}
and finally I have a list comprised of all the categories, as follows:
struct category catList[] = {words, lines, characters};
when I access the members of these structs by name, I have no issues. But if I try to access them in a loop, via catList[i].member, the member count always returns 0. the other two members, name and namelen, behave correctly withing the loop, and accessing count from outside the loops returns correctly. If anyone would be willing to help me understand what's going on I would greatly appreciate it.
if it is necessary, here is my full program:
#include <stdio.h>
#include <string.h>
int get_width(char* word) {
return 15 - strlen(word);
}
struct category {
char *name;
int namelen;
int count;
};
struct category createCat(char *name) {
struct category cat = {name, get_width(name), 0};
return cat;
}
int main () {
int c;
int inside_word;
int i;
int p;
struct category words = createCat("words");
struct category lines = createCat("lines");
struct category characters = createCat("characters");
struct category catList[] = {words, lines, characters};
while ((c = getchar()) != EOF) {
characters.count++;
if (c != '\n' && c != ' ' && c != '\t') {
putchar(c);
if (!inside_word) {
inside_word = 1;
words.count++;
}
}
else {
if (inside_word)
printf("\n");
inside_word = 0;
if (c == '\n')
lines.count++;
}
}
printf("\n%d words, %d lines, %d characters\n",
words.count, lines.count, characters.count);
for (i = 0; i < 3; i++) {
printf("%s:%*s", catList[i].name, catList[i].namelen, " ");
printf("%d", catList[i].count);
for ( p = 0; p < catList[p].count; p++)
printf("#");
printf("\n");
}
return 0;
}

Answer 1

When you do this:
struct category catList[] = {words, lines, characters};
You are copying the 3 structs' data into the catList. So when you update the 3 structs by their names, the ones in the catList are different copies and would not be updated.
To resolve this, I would recommend using pointer types. There are two ways of doing this.
You can return a pointer in the createCat method.
struct category* createCat(char *name) {
struct category* cat = (struct category*) malloc(sizeof(struct category));
//...
return cat;
}
From this point on, always use pointer for storing. This is quite commonly used.
You can store the pointer in the array catList:
struct category *catList[] = {&words, &lines, &characters};
and when you use them in the loop, use like:
catList[i]->count++;

Answer 2

You are copying the words, lines, characters structures into your list.
But you do this before you process the data, so they never get updated.
If you want to maintain both sets of structures, you must update them in your loop:
words.count++;
catList[0].count++;
If you want to maintain a single set, delete the other. (Pretty much what you have now, except for the top and bottom.)
If you want them to share data, then use pointers, so the list (or the stand-alone variables) point to the other structure.