I am trying to make changes to an array of structures. My code is as follows:

```
typedef struct {
    char firstName[30];
    char lastName[30];
    char street[35];
    char city[20];
    char state[3];
    int zip;
    char phone[15];
    int accountId;
} Customer;

struct Customer customer_list[];

//void copy_first_name(char data[], int i) {
//  strcpy(customer_list[i].)

//}

int main(void) {

    int _zip, _accountId;
    char _firstName[30], _lastName[30], _street[35], _city[20], _state[3], _phone[15];

    for (int i = 0; i < 10; i++) {

        printf("Enter data for customer %d: \n", i);
        printf("Enter First Last Phone: ");
        scanf("%s%s%s", &_firstName, &_lastName, &_phone);

        printf("\nEnter Address (Street City State ZIP): ");
        scanf("%s%s%s%d", &_street, &_city, &_state, &_zip);

        strcpy(customer_list[i].firstName, _firstName);

    }

    return 0;
}

```

I get the error message in the title, referring to customer\_list. Can anyone help me out?