I have 3 .h and 3.cpp files. When I run them it does not Displaying all students, Displaying invalid emails, and Displaying average days in course. But it does display Displaying by degree program(which is good). 
part 1:Degree.h:
#pragma once
#include <string>
enum class DegreeProgram {SECURITY, NETWORK, SOFTWARE };
static const std::string DegreeProgramStr[] = {"SECURITY", "NETWORK", "SOFTWARE"};
Student.h:
#pragma once
#include <iostream>
#include <iomanip>
#include "Degree.h"

class Student {
public:
    static const int daysToCompleteCourses = 3; // Array holding number of days to complete each course
private:
    std::string studentID;
    std::string firstName;
    std::string lastName;
    std::string emailAddress;
    int age;
    int numberOfDays[daysToCompleteCourses];
    DegreeProgram degreeProgram;
public:
    Student(); // Default constructor
    Student(std::string studentID, std::string firstName, std::string lastName, std::string emailAddress, int age, int numberOfDays[], DegreeProgram degreeProgram); // Parameterized constructor
    ~Student(); // Destructor
    
    // Accessor (getter) functions
    std::string getStudentID();
    std::string getFirstName();
    std::string getLastName();
    std::string getEmailAddress();
    int getAge();
    int* getNumberOfDays();
    DegreeProgram getDegreeProgram();

    // Mutator (setter) functions
    void setStudentID(std::string studentID);
    void setFirstName(std::string firstName);
    void setLastName(std::string lastName);
    void setEmailAddress(std::string emailAddress);
    void setAge(int age);
    void setNumberOfDays(int numberOfDays[]);
    void setDegreeProgram(DegreeProgram dp);
    // Other functions
    void print();
};
Student.cpp:
#include "Student.h"

// Default constructor
Student::Student() {
    studentID = "";
    firstName = "";
    lastName = "";
    emailAddress = "";
    age = 0;
    for (int i = 0; i < daysToCompleteCourses; i++) numberOfDays[i] = 0;
    degreeProgram = DegreeProgram::SECURITY;
}

// Parameterized constructor
Student::Student(std::string studentID, std::string firstName, std::string lastName, std::string emailAddress, int age, int numberOfDays[], DegreeProgram degreeProgram) {
    this->studentID = studentID;
    this->firstName = firstName;
    this->lastName = lastName;
    this->emailAddress = emailAddress;
    this->age = age;
    for (int i = 0; i < daysToCompleteCourses; i++) this->numberOfDays[i] = numberOfDays[i];
    this->degreeProgram = degreeProgram;
}

// Destructor
Student::~Student() {
    // Empty for now
}

// Accessor implementations
std::string Student::getStudentID() { return studentID; }
std::string Student::getFirstName() { return firstName; }
std::string Student::getLastName() { return lastName; }
std::string Student::getEmailAddress() { return emailAddress; }
int Student::getAge() { return age; }
int* Student::getNumberOfDays() { return numberOfDays; }
DegreeProgram Student::getDegreeProgram() { return degreeProgram; }

// Mutator implementations
void Student::setStudentID(std::string studentID) { this->studentID = studentID; }
void Student::setFirstName(std::string firstName) { this->firstName = firstName; }
void Student::setLastName(std::string lastName) { this->lastName = lastName; }
void Student::setEmailAddress(std::string emailAddress) { this->emailAddress = emailAddress; }
void Student::setAge(int age) { this->age = age; }
void Student::setNumberOfDays(int numberOfDays[]) {
    for (int i = 0; i < daysToCompleteCourses; i++) this->numberOfDays[i] = numberOfDays[i];
}
void Student::setDegreeProgram(DegreeProgram dp) { this->degreeProgram = dp; }

// print() to print specific student data
void Student::print() {
    std::cout << "Student ID: " << getStudentID() << "\t";
    std::cout << "First Name: " << getFirstName() << "\t";
    std::cout << "Last Name: " << getLastName() << "\t";
    std::cout << "Email: " << getEmailAddress() << "\t";
    std::cout << "Age: " << getAge() << "\t";
    std::cout << "Days in Course: {" << getNumberOfDays()[0] << ", " << getNumberOfDays()[1] << ", " << getNumberOfDays()[2] << "}\t";
    std::cout << "Degree Program: " << DegreeProgramStr[static_cast<int>(getDegreeProgram())] << std::endl;
}