how to pass parameter as a pointer to an array in c

Question

To start, none of the existing solutions I have looked through have the parameter as an array, such as:

void inputCars(Car * cars[], int size);

Here is the code I currently have.

/******************************************************************************
WE WANT:
dynamic array of pointers to a
car structure
*******************************************************************************/
#include <string.h>
#include <stdio.h>

typedef struct {
 char make[60];
 double price;
 int year;
}Car;

int size;

void inputCars(Car* cars[], int size);

int main(int argc , char** args)
{
    printf("Enter how many Cars you wish to take inventory of: ");
    scanf("%d", &size); 
    Car cars[size];
    inputCars(&(cars), size);

}

void inputCars(Car * cars[], int size)
{
    for(int i = 0; i < size; i++)
    {
           // TODO
    }
    
}

When I try to put the cars array through I get the following error :

 expected 'struct Car**' but argument is of type 'struct Car(*)[(sizetype)(size)]'

I understand what Car * cars[] is asking, thanks for the help with that, but I am confused on how I can pass this through.

I am not allowed to change the way the parameters are in the function and am utterly confused as to how to pass the array through.

Answer 1

In this statement

Car cars[size];

there is declared a variable length array.

In this call

inputCars(&(cars), size);

the expression &cars has the type Car( * )[size]. But the corresponding function parameter

void inputCars(Car* cars[], int size);

is declared like Car * cars[] that is adjusted by the compiler to the type Car ** and there is no implicit conversion from one pointer type to another. So the compiler issues an error message.

In the comment to your program there is written

WE WANT:
dynamic array of pointers to a
car structure

So instead of declaring a variable length array you need to allocate dynamically an array of pointers to objects of the type Car. Something like

Car **cars = malloc( size * sizeof( Car * ) );

for ( int i = 0; i < size; i++ )
{
    cars[i] = malloc( sizeof( Car ) );
}

In this case the function can be called like

inputCars( cars, size );