Check Structure, add items if not already in structure. C - c

Question

I'm trying to do some practice programming and I've come to a, for me, a difficult problem.
The problem is I'm supposed to write a program the will take the make and model of a car that was "entered" and place it in the structure, if the make an model are not there, otherwise it does nothing.
This is what I have so far, and I keep getting errors:
#include <stdio.h>
#include <string.h>
void addCar(struct car u, int* count, char *make[], char *model[]);
struct car { char make[30]; char model[30]; };
int main(void)
{
struct car unique[10] = {{"Ford", "Explorer"}, {"Honda", "Civic"},
{"Honda", "Accord"}, {"Chevy", "Malibu"}};
int i, count = 4;
addCar(unique, &count, "Ford", "Mustang");
}
void addCar(struct car u, int* count, char *make[], char *model[])
{
}
The line that says addCar(unique, &count,... it's saying "Argument type 'struct car' is incomplete" and the last line says "conflicting types for addCar"
Could you all give me a few pointers, please?
EDIT:
Okay, here is what my code is now, but I still can't get it to work. Any other suggestions would be appreciated!
#include <stdio.h>
#include <string.h>
struct car { char make[30]; char model[30]; };
void addCar(struct car *u, int *count, char *make, char *model);
int main(void)
{
struct car unique[10] = {{"Ford", "Explorer"}, {"Honda", "Civic"},
{"Honda", "Accord"}, {"Chevy", "Malibu"}};
int i, count = 4;
printf("%s", unique[0].make);
addCar(unique, &count, "Ford", "Mustang");
}
void addCar(struct car *u, int *count, char *make, char *model)
{
int i = 0;
for (i; i < *count; i++)
{
if ((u[i].make != make) && (u[i].model != model))
{
strcpy(u->make, make);
strcpy(u->model, model);
count++;
}
}
for (i = 0; i < *count; i++)
printf("%s, %s", u[i].make, u[i].model);
}

Answer 1

struct car unique[10] = {{"Ford", "Explorer"}, {"Honda", "Civic"},
{"Honda", "Accord"}, {"Chevy", "Malibu"}};
This is an array of struct car, therefore, you need to declare your addCar function as follow
void addCar(struct car *u, int *count, char *make, char *model)
*make and *model represent 2 strings. You have a mistake when you have char *make[], which declares an array of string.

Answer 2

Your function prototype for addCar is defined and uses 'struct car' before you define 'struct car'. Try moving the structure definition above the prototype for addCar.

Answer 3

Here are a few things that I figured out when looking at your code.
In this case, I think it's best if you use while loop rather than for loop.
Secondly, if you want to make sure that the car you want to add does not exist in the list, I suggest you use this
while (i < *size) {
if ((u[i].make == make) && (u[i].model == model)) { break; } // check if the car is already in the list
i++;
}
It checks the whole list for the existence of an element with the same make and model.
Here is the code I modified from yours. I hope it helps you.
#include <stdio.h>
#include <string.h>
struct car { char make[30]; char model[30]; };
void addCar(struct car *u, int *count, char *make, char *model);
int main(void)
{
struct car unique[10] = {{"Ford", "Explorer"}, {"Honda", "Civic"},
{"Honda", "Accord"}, {"Chevy", "Malibu"}};
int i, count = 4;
addCar(unique, &count, "Ford", "Mustang");
for (i = 0; i < count; i++) {
printf("%s, %s\n", unique[i].make, unique[i].model);
}
}
void addCar(struct car *u, int *size, char *make, char *model)
{
int i = 0;
while (i < *size) {
if ((u[i].make == make) && (u[i].model == model)) { break; } // check if the car is already in the list
i++;
}
if (i == *size) { // car found
struct car c;
strcpy(c.make, make);
strcpy(c.model, model);
u[i] = c;
(*size)++;
}
}