Not showing output after creating nodes? - c++

Question

Hey ! i am trying to create a program of hospital management system using doubly linked list in c++.
in this i am using whole class for patient data.
i created a nodes for linked list .
i am using one node to represent one bed in hospital.
but after that when i am trying to print some data manually , nothing is printing in console and program is ending without showing any output
this is my code :
#define max_limit 25;// maximum 50 beds can be there in hospital
using namespace std;
class patient //creating class to store the data of patient
{
public:
int pt_id;
string pt_name; //patient name
string diagnosis; //diagnosis patient have
};
struct bed //each bed in hospital
{
class patient p;
struct bed *prev;
struct bed *next;
};
int main()
{
//creating 3 beds in starting only and giving values.
struct bed *head=(struct bed *)malloc(sizeof(patient));
struct bed *second=(struct bed *)malloc(sizeof(patient));
struct bed *tail=(struct bed *)malloc(sizeof(patient));
head->prev=NULL;
head->p.pt_id=6478;
head->p.pt_name="Jayraj";
head->p.diagnosis="Headaches";
head->next=second;
second->prev=head;
second->p.pt_id=8933;
second->p.pt_name="Mayank";
second->p.diagnosis="Highfever";
second->next=tail;
tail->prev=second;
tail->p.pt_id=1788;
tail->p.pt_name="Jay";
tail->p.diagnosis="Stomacheache";
tail->next=NULL;
cout<<"Size:"<<sizeof(patient);
return 0;
}```

Answer 1

You should check the errors - make sure your environment displays them. There are at least these issues:
When allocating a bed you shouldn't use sizeof(patient), but sizeof(bed).
define should not end with a semi-colon.
As a bed could be empty, you'd better define the p member as a pointer to a patient instance
You're not using C++ syntax:
Use new instead of malloc.
Define constructors and methods
Use nullptr instead of NULL
Use PascalCase for class names
Here is some code for inspiration, but you'll need to add more logic to it for your assignment (e.g. you'll have to verify the limit of beds):
#define max_limit 25 // maximum 25 beds allowed in hospital
using namespace std;
class Patient
{
public:
int pt_id;
string pt_name; //patient name
string diagnosis; //diagnosis patient have
// Constructor:
Patient(int id, string name, string diag) :
pt_id(id), pt_name(name), diagnosis(diag) {}
};
class Bed
{
public:
Patient* p = nullptr;
Bed* prev = nullptr;
Bed* next = nullptr;
// Constructors:
Bed() {};
Bed(Patient* p) : p(p) {};
// Method to ease linking beds
Bed* prepend(Bed* other) {
other->next = this;
this->prev = other;
return other;
};
};
int main()
{
// Use constructor to create patients
Patient *jaray = new Patient(6478, "Jayraj", "Headaches");
Patient *mayank = new Patient(8933, "Mayank", "Highfever");
Patient *jay = new Patient(1788, "Jay", "Stomacheache");
// Use constructor and method to create linked list
Bed *beds = (new Bed(jay))
->prepend(new Bed(mayank))
->prepend(new Bed(jaray));
// Let's output something: the beds with patient names
Bed *bed = beds;
while (bed != nullptr) {
if (bed->p == nullptr) {
cout << "bed without patient\n";
} else {
cout << "bed occupied by " << bed->p->pt_name << "\n";
}
bed = bed->next;
}
return 0;
}