Problem in swapping of array indexes

[redfury]

Hello, I was supposed to make a student database. I have made the code however, there is one problem which I am facing and I have been unable to solve it.
The problem is with the deletion function...
First, here is the code

#include <iostream>
#include <string>
#include <iomanip>
using namespace std;
void initialize();
void print(int);
void printstu(int);
bool menu();
void update();
void add();
void semsearch();
void namesearch();
void deleteinfo();
void duplicate();
struct date {
	int d;
	int m;
	int y;
	void input()
	{
		cin >> d >> m >> y;
	};
};
enum extracurricularSkill { SocietyMember, Sportsman, InternetGeek, None };
void printenum(extracurricularSkill);
struct student {
	int id;
	string name;
	date dob;
	char gen;
	int sem;
	string dep;
	float gpa;
	extracurricularSkill extra;
	void input()
	{
		cout << "Enter ID: ";
		cin >> id;
		getchar();
		cout << "Enter Nmae: ";
		getline(cin, name);
		cout << "Enter Date of Birth (D/M/Y): ";
		dob.input();
		cout << "Enter Gender: ";
		cin >> gen;
		cout << "Enter Semester: ";
		cin >> sem;
		getchar();
		cout << "Enter Department: ";
		getline(cin, dep);
		cout << "Enter GPA: ";
		cin >> gpa;
		int a;
		cout << "Pick the Extracurricular Skill, " << endl
			<< "1) SocietyMember" << endl
			<< "2) Sportsman" << endl
			<< "3) InternetGeek" << endl
			<< "4) None" << endl
			<< "Enter skill: ";
		cin >> a;
		a--;
		extra = (extracurricularSkill)a;
	}
	void output()
	{
		cout << left << setw(6) << id;
		cout << left << setw(20) << name;
		cout << left << setw(10) << gen;
		cout << left << setw(3) << dob.d << setw(3) << dob.m << setw(14) << dob.y;
		cout << left << setw(15) << sem;
		cout << left << setw(15) << dep;
		cout << left << setw(10) << gpa;
		cout << left << setw(30);
		printenum(extra);
		cout << endl;
	}
};
int num = 5;
student *s = new student[num];
int main()
{
	initialize();
	bool fh = true;
	while (fh)
	{
		fh = menu();
	}
	cout << endl;
	system("pause");
	return 0;
}
void initialize()
{
	for (int i = 0, j = 1; j <= 5; j++, i++)
	{
		s[i].id = j;
		s[i].gen = 'M';
		s[i].gpa = 3.14;
		s[i].sem = j;
		s[i].dep = "CS";
		s[i].dob.d = j + 20;
		s[i].dob.m = j + 1;
		s[i].dob.y = 1999 - j;
		s[i].extra = InternetGeek;
	}
	s[0].name = "Ahmed Nadeem";
	s[1].name = "Zurriat Baloch";
	s[2].name = "Ahmed Nadeem";
	s[2].id = 1; 
	s[3].name = "Mamoon Amin";
	s[4].name = "Tahir Baloch";
	s[2].sem = 1; 
	s[1].gen = 'F';
	s[1].dep = "BBA";
	s[4].dep = "EE";
}
bool menu()
{
	cout << right << setw(50) << "Student Database" << endl;
	cout << endl << "1) Display Information of all students" << endl
		<< "2) Update Information of an existing student" << endl
		<< "3) Add information of a new student" << endl
		<< "4) Search and display specific student's information by NAME" << endl
		<< "5) Search and display specific student's information by SEMESTER and DEPARTMENT" << endl
		<< "6) Delete a student's record" << endl
		<< "7) Search for Duplicated Entries" << endl
		<< "8) " << endl
		<< "9) Quit the Porgram" << endl << endl;
	cout << "Please Enter Your Selection: ";
	int ch;
	cin >> ch;
	switch (ch)
	{
	case 1:
		print(0);
		break;
	case 2:
		update();
		break;
	case 3:
		add();
		break;
	case 4:
		namesearch();
		break;
	case 5:
		semsearch();
		break;
		case 6:
			deleteinfo();
			break;
		case 7:
			duplicate();
			break;
	case 8:
		break;
	case 9:
		return false;
		break;
	default:
		cout << "You entered an invalid choice. Please enter again";
		break;
	}
	return true;
}
void print(int a)
{
	int sem = -1;
	string dep = "None";
	if (a == 1)
	{
		cout << "Enter Semester: ";
		cin >> sem;
	}
	if (a == 2)
	{
		getchar();
		cout << "Enter Department: ";
		getline(cin, dep);
	}
	cout << left << setw(6) << "ID";
	cout << left << setw(20) << "Name";
	cout << left << setw(10) << "Gender";
	cout << left << setw(20) << "Date of Birth";
	cout << left << setw(15) << "Semester";
	cout << left << setw(15) << "Department";
	cout << left << setw(10) << "GPA";
	cout << left << setw(30) << "Extracurricular Skill";
	cout << endl << endl;
	for (int i = 0; i < num; i++)
	{
		if (a == 1 && s[i].sem == sem)
		{
			s[i].output(); 
		}
		else if (a == 2 && dep == s[i].dep)
		{
			s[i].output();
		}
		else if (a == 0)
		{
			s[i].output();
		}
	}
}
void printstu(int i)
{
	cout << "ID: " << s[i].id << endl;
	cout << "Name: " << s[i].name << endl;
	cout << "Gender: " << s[i].gen << endl;
	cout << "Semester: " << s[i].sem << endl;
	cout << "Department: " << s[i].dep << endl;
	cout << "GPA: " << s[i].gpa << endl;
	cout << "Extracurricular Skill: ";
	printenum(s[i].extra);
	cout << endl << endl;
}
void duplicate()
{
	bool fh = true; 
	for (int i = 0; i < num; i++)
	{
		for (int j = i+1; j < num; j++)
		{
			if (s[i].name == s[j].name && s[i].id == s[j].id && s[i].gen == s[j].gen && s[i].sem == s[j].sem && s[i].dep == s[j].dep && s[i].gpa == s[j].gpa && s[i].extra == s[j].extra)
			{
				swap(s[i], s[num = 1]);
				num--; 
				fh = false; 
			}
		}
	}
	if (fh == false)
	{
		cout << endl << "Duplicate Entry found and deleted. ";
	}
	else
		cout << endl << "No Duplicate Entry found."; 
	cout << endl << endl << "Press Enter to continue";
	getchar(); 
}
void printenum(extracurricularSkill extra)
{
	switch (extra)
	{
	case 0:
		cout << "SocietyMember";
		break;
	case 1:
		cout << "Sportsman";
		break;
	case 2:
		cout << "InternetGeek";
		break;
	default:
		cout << "None";
		break;
	}
}

The problem that is occurring is with duplicate() function and the print(int a = 0) function.
I have made a duplicate entry in my code... This is what you get when you press 1 at start of program.

                            Student Database

1) Display Information of all students
2) Update Information of an existing student
3) Add information of a new student
4) Search and display specific student's information by NAME
5) Search and display specific student's information by SEMESTER and DEPARTMENT
6) Delete a student's record
7) Search for Duplicated Entries
8)
9) Quit the Porgram

Please Enter Your Selection: 1
ID    Name                Gender    Date of Birth       Semester       Department     GPA       Extracurricular Skill   

1     Ahmed Nadeem        M         21 2  1998          1              CS             3.14      InternetGeek            
1     Ahmed Nadeem        M         23 4  1996          1              CS             3.14      InternetGeek            
4     Mamoon Amin         M         24 5  1995          4              CS             3.14      InternetGeek             

As you can see, the entry number 1 and 3 are same... So, when I press 7, it is supposed to delete the entry number 1.
And now, when I do press 7, it does show that the duplicate entry has been deleted but when I again press 1 now, it shows no users... I am unable to understand the problem here. From what I get, it should show all the other remaining entries but it shows no entry now...
This is what I get after pressing 7 and then 1

Please Enter Your Selection: 7

Duplicate Entry found and deleted.

Student Database

1) Display Information of all students
2) Update Information of an existing student
3) Add information of a new student
4) Search and display specific student's information by NAME
5) Search and display specific student's information by SEMESTER and DEPARTMENT
6) Delete a student's record
7) Search for Duplicated Entries
8)
9) Quit the Porgram

Please Enter Your Selection: 1
ID    Name                Gender    Date of Birth       Semester       Department     GPA       Extracurricular Skill   
 

Can someone help and identify the problem, please?
Thank you!
(I have deleted some of the code and some of the irrelevant output because of length limit)

[Grime]

You've written this in duplicate():

swap(s[i], s[num = 1]);
num--;

That is read by the compiler as:

num = 1;
swap (s[i], s[1]);
num = 0;

That's why your program thinks there are 0 students.

I'm not sure what the logic behind using swap() is. But I can tell you that you probably want to delete s[j] from the array.

Not sure if there's some function in the standard library to help implement that. If not you can always do something like this:

for (int i = to_delete + 1; i < num; i++) {
    arr[i - 1] = arr[i];
} // to_delete is the index to be deleted from the array 

[redfury]

Oh, God!
I didn't put a '=' there, I instead put a '-' there..
It was supposed to swap that index with the last index and then I reduced the array indexes by 1 (by reducing num which was controlling the total number of indexes).

Thanks a lot for pointing this out, I might have just spent even more time trying to figure out what I did wrong and what other method could I use :/
And thanks for the code too! ^_^ It would work perfectly as well!