Question

Hi, i'm creating a c++ program with a linked list of Employees, i'm running into issues as far as displaying programmers only portion and the average salary of all the employees. Please make any changes or comments !

Employee.h file:

#ifndef EMPLOYEE_H

#define EMPLOYEE_H

#include

using namespace std;

enum Role {programmer, manager, director};

struct Employee

{

std::string firstName;

std::string lastName;

int SSN;

std::string department;

double salary;

Role role;

};

#endif

#ifndef NODE_H

#define NODE_H

Node.h file:

#include "Employee.h"

typedef Employee EMP;

struct Node

{

EMP e;

Node * next;

Node();

Node(EMP);

Node(EMP,Node* next);

};

Node::Node()

{

next=NULL;

}

Node::Node(EMP e_data)

{

e=e_data;

}

Node::Node(EMP e_data, Node* next)

{

e=e_data;

this->next= next;

}

#endif

Main cpp file:

#include <iostream>

#include <cstdlib>

#include <ctime>

#include "Employee.h"

#include "Node.h"

using namespace std;

void setSalary (Employee& emp)

{

emp.salary= 45000+rand() %20000; // generates salary for employee

}

void setRoles(Employee& emp)

{

emp.role = static_cast(rand()%3); // gives employee job title

}

void setSSN (Employee& emp)

{

// int y = x;

emp.SSN =rand()%499999999+400000000; // sets employee SSN

}

void setFirst( Employee& emp, string* name)

{

int y = rand()%5;

emp.firstName = name[y]; //gives random first name

}

void setLast(Employee& emp, string* name)

{

int y = rand()%5;

emp.lastName = name[y]; // gives random last name

}

void setDepartment(Employee& emp, string * dep)

{

int y = rand()%3;

emp.department= dep[y]; //gives employee random department

}

int main()

{

srand(time(NULL)); // random number generator

double avgSalary; // initialize Average Salary

Node* head= NULL; // starting node

Node* prev= NULL; // node next to the last one

Employee e; // object instance

// array of names, roles(job titles), and departments

string roleType [3] = {"programmer", "manager", "director"};

string firstName[5] = {"John", "James", "Joe", "Jessica", "Juno" };

string lastName[5] = {"Smith", "Williams", "Jackson", "Jones", "Johnson" };

string department[5]= {"Accounting", "IT", "Sales" };

// Create linked list of employees

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

{

Employee e;

// function calls (roles, salary ...etc)

setFirst(e, firstName);

setLast(e, lastName);

setSSN(e);

setSalary(e);

setRoles(e);

setDepartment(e, department);

// creates nodes for employees

Node*temp = new Node(e);

if (i ==0)

{

head=temp;

prev= temp;

}

else

{

prev->next= temp;

prev = temp; // links the nodes together

}

}

// Display information of all Employees

cout<<"======== Employee Data======="<

prev = head; // starting at the first node

while(prev !=NULL)

{

cout<<(prev->e).firstName<< " ";

cout<<(prev->e).lastName<< " ";

cout<<(prev->e).SSN<< " ";

cout<<(prev->e).salary<< " ";

cout<<(prev->e).department<< " ";

cout

prev= prev->next;

}

cout<<" \n \n";

//

cout<<"======== Programmer Only Data======="<

prev = head; // starts at beginning of linked list

while(prev !=NULL)

{

if (prev->e.role == 0) // checks to see if role is 0 or programmer

cout<<(prev->e).firstName<< " ";

cout<<(prev->e).lastName<< " ";

cout<<(prev->e).SSN<< " ";

cout<<(prev->e).salary<< " ";

cout<<(prev->e).department<< " ";

cout

prev= prev->next; // moves on to next node

// else {

// break;

// }

}

//Computes Average Salary

prev = head; // starts at the first node

while ( prev !=NULL)

{

avgSalary += (prev->e).salary;

prev = prev->next;

}

// Display Average Salary

cout<< "Average Salary: "<< (avgSalary)/5 << "\n";

// Deallocate memory

Node* temp = head;

Node* tail;

while (temp !=NULL)

{

tail=temp->next;

delete temp;

temp = tail;

}

head=NULL;

if (head == NULL )

{

cout<<" List Deleted \n";

}

}

Answer 1

Here the issue was that the next pointer of the new node which is created was not being set to nullptr because of which it was pointing to garbage location. I have included the comment in the main function where the change is made.

Code:

int main()

{

   srand(time(NULL)); // random number generator

   double avgSalary = 0.0; // initialize Average Salary

   Node* head = NULL; // starting node

   Node* prev = NULL; // node next to the last one

   Employee e; // object instance

   // array of names, roles(job titles), and departments

   string roleType[3] = { "programmer", "manager", "director" };

   string firstName[5] = { "John", "James", "Joe", "Jessica", "Juno" };

   string lastName[5] = { "Smith", "Williams", "Jackson", "Jones", "Johnson" };

   string department[5] = { "Accounting", "IT", "Sales" };

   // Create linked list of employees

   for (int i = 0; i < 10; i++)

   {

       Employee e;

       // function calls (roles, salary ...etc)

       setFirst(e, firstName);

       setLast(e, lastName);

       setSSN(e);

       setSalary(e);

       setRoles(e);

       setDepartment(e, department);

       // creates nodes for employees

       Node*temp = new Node(e);
       //We have to make the next pointer of the node as nullptr as we are checking
       //For null to determine the end of the list
       //If we do not put the next pointer of the node as nullptr it will have garbage value.
       temp->next = nullptr;

       if (i == 0)

       {

           head = temp;

           prev = temp;

       }

       else

       {

           prev->next = temp;

           prev = temp; // links the nodes together

       }

   }

   // Display information of all Employees

   cout << "======== Employee Data=======";

       prev = head; // starting at the first node

   while (prev != NULL)

   {

       cout << (prev->e).firstName << " ";

       cout << (prev->e).lastName << " ";

       cout << (prev->e).SSN << " ";

       cout << (prev->e).salary << " ";

       cout << (prev->e).department << " ";

       prev = prev->next;
       cout << " \n \n";

   }

   //

   cout << "======== Programmer Only Data=======";

       prev = head; // starts at beginning of linked list

   while (prev != NULL)

   {

       if (prev->e.role == 0) // checks to see if role is 0 or programmer

           cout << (prev->e).firstName << " ";

       cout << (prev->e).lastName << " ";

       cout << (prev->e).SSN << " ";

       cout << (prev->e).salary << " ";

       cout << (prev->e).department << " ";

       prev = prev->next; // moves on to next node

       cout << "\n\n";

   }

   //Computes Average Salary

   prev = head; // starts at the first node

   while (prev != NULL)

   {

       avgSalary += (prev->e).salary;

       prev = prev->next;

   }

   // Display Average Salary

   cout << "\n\nAverage Salary: " << (avgSalary) / 5 << "\n";

   // Deallocate memory

   Node* temp = head;

   Node* tail;

   while (temp != NULL)

   {

       tail = temp->next;

       delete temp;

       temp = tail;

   }

   head = NULL;

   if (head == NULL)

   {

       cout << "\n List Deleted \n";

   }

}

OUTPUT: