Dynamic fscanf into an array - c

Question

I am trying to place some text into a structure part of my array is a array which takes part of the text.
For example my structure is:
struct animal
{
char animal_Type[11];
int age;
int numberOfLegs;
int walksPerDay;
char favoriteFood[];
};
I will then have input such as:
dog,2,4,2,biscuits,wet
cat,5,4,0,biscuits,wet,dry,whiskers
bird,1,2,0,birdseed,biscuits,bread,oats,worms,insects,crackers
I have a working solution that places all the values up to walks per day into the structure, however I want to be able to place the food items into Favorite food. I have a dynamic array for this, but i'm not sure how to read remaining text into the favoriteFood array.
The code used is:
fp = open("animals.txt","r");
struct animal *animal = malloc(sizeof(sturct animal)*3);
int i = 0;
if(fp != NULL) {
while(i < 3) {
fscanf(fp,"%s %d %d %d %s",
animal[i].animal_Type,
animal[i].age,
animal[i].numberOfLegs,
animal[i].walksPerDay,
animal[i].favoriteFood); // need to be able to enter the string of food into here
i++
}
How would I go about doing this?

Answer 1

First of, your struct doesn't match what you've said in the comments.
char favoriteFood[];
The above is an array of char, so couldn't possibly hold a list of favourite foods except if it were one string. And since the size of the array is unspecified, you'd not be able to fill it like you have been either. Instead what you actually want is
char **favoriteFood;
unsigned int favoriteFoodSize;
That will let you create an expanding list of strings to fit whatever data you need to accommodate.
As for reading it in, the best way would be to read the entire line in using fgets and then use something like strtok to break the line up by your separator character. First define a very large string to hold the entire line and a char * to hold each field.
char buffer[1024];
char *token;
And then to the main loop would be something like this:
while(fgets(buffer,1024,fp)) {
token=strtok(buffer,",");
strcpy(beasts[i].animal_Type,token);
token=strtok(NULL,",");
beasts[i].age = atoi(token);
/* etc... */
}
You'd need to check whether token is ever NULL to cope with the possibility of short lines and handle it accordingly. And also make sure that the string copied into animal_Type isn't longer than 10 characters...or alternative make it a char * so you can have any size of string.
For the favoriteFood, you'll need to use realloc to increase the size of it to accommodate each new food added and keep going through the string until you run out of tokens.
token=strtok(NULL,",");
if(token) {
beasts[i].favoriteFood=malloc(sizeof(char *));
beasts[i].favoriteFood[0]=strdup(token); // Need to index using 0 as favoriteFoodSize won't have a value yet
beasts[i].favoriteFoodSize=1;
token=strtok(NULL,",");
while(token) {
beasts[i].favoriteFood=realloc(beasts[i].favoriteFood,(beasts[i].favoriteFoodSize+1)*sizeof(char *));
beasts[i].favoriteFood[beasts[i].favoriteFoodSize]=strdup(token);
beasts[i].favoriteFoodSize++;
token=strtok(NULL,",");
}
}
The last food will have a \n in it as fgets keeps it in the buffer it reads, so you could use that to tell if you've finished processing all the foods (you will also need to remove it from the last food). Or if you don't have it, you know the line was longer and you'll need to read more in. But that seems unlikely based on your sample data.
And since you're doing lots of memory allocation, you should ensure that you check the values returned to make sure you've not run out of memory.