C++ File handling Program

Question

Here I have tried to write a program write, update, display, delete, and print record. Display a menu of option and select an option to execute it. Problem is that, "Neither default switch statement is executed nor 3 to 6 option executed."

Can someone point out the error/mistakes?

 #include <iostream>
#include <fstream>
#include <windows.h>
#include <iomanip>

using namespace std;

void gotoxy(short x, short y) {
COORD pos = {x, y};
SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), pos);
}

struct data{

char mark;
char name[15],city[15];

};

class person{
public:
    void addrec(void);
    void update(void);
    void disp_all(void);
    void display(void);
    void delrec(void);
    void pack(void);

};
int main(){
person obj;
int ch;
while(1){
    system("cls");
    gotoxy(28,5);
    cout<<"Person Records";
    gotoxy(25,6);
    cout<<"===================="; //20
    gotoxy(25,7);
    cout<<"1:   Add Records ";
    gotoxy(25,8);
    cout<<"2:   Update Records ";
    gotoxy(25,9);
    cout<<"3:   Display All Records ";
    gotoxy(25,10);
    cout<<"4:   Display Single Records ";
    gotoxy(25,11);
    cout<<"5:   Mark  Record for Deletion ";
    gotoxy(25,12);
    cout<<"6:   Delete Records Permanently";
    gotoxy(25,13);
    cout<<"7:   Exit ";
    gotoxy(25,15);
    cout<<"Enter Your choice  [1-7]  ";
    cin>>ch;

    switch(ch){
    case 1: obj.addrec(); break;
    case 2: obj.update(); break;
    case 3: obj.disp_all(); break;
    case 4: obj.display(); break;
    case 5: obj.delrec(); break;
    case 6: obj.pack(); break;
    case 7: exit(1); break;
    default:
        cout<<"invalid choice ";
    }
}
}

void person::addrec(void){
    data rec;
    char op;
    ofstream add("employee.dat",ios::binary);
    do{
        system("cls");
        cout<<"Enter Name of person: ";
        cin>>rec.name;
        cout<<"Enter City of person: ";
        cin>>rec.city;
        rec.mark=' ';

        add.write((char*)&rec,sizeof(rec));
        cout<<"More Records [Y/N]";
        cin>>op;
    }
    while(op=='y'||op=='Y');

    add.close();
}



void person::update(){
data rec;
char nm[15];
long int rn=0, t=0;

 fstream update_Rec("employee.dat", ios::binary|ios::in|ios::out);

 if(!update_Rec){
    cerr<<"File opening error "<<endl;
    exit(1);
 }

 cout<<"Enter Name of person ";
 cin>>nm;

 while(update_Rec.read((char*)&rec,sizeof(rec))){
    if(strcmp(nm,rec.name)==0){
            cout<<rec.mark<<rec.name<<"\t"<<rec.city<<endl;
        rn=(rn)&sizeof(rec);
    update_Rec.seekp(rn);
    cout<<"Enter New name of person";
    cin>>rec.name;
    cout<<"Enter new city of Person";
    cin>>rec.city;

    update_Rec.write((char*)&rec,sizeof(rec));

    update_Rec.close();

    t=1;
    }
rn++;
 }
if(t==0)
    cout<<"Record not found"<<endl;

}

void person::disp_all(void){

data rec;
char op;
ifstream disp_all_Rec("employee.dat",ios::binary);

if(!disp_all_Rec){
    cerr<<"File opening error";
    exit(1);
}
while(!disp_all_Rec.eof()){
    disp_all_Rec.read((char*)&rec,sizeof(rec));
    cout<<setw(15)<<bodyrec.mark<<rec.name<<setw(15)<<rec.city<<endl;
}
disp_all_Rec.close();
}


void person::display(void){

data rec;
char nm[15];

long int rn=0, t=0;

ifstream display_Rec("employee.dat",ios::binary);
if(!display_Rec){
    cerr<<"File opening error";
    exit(1);
}
cout<<"Enter name of person: ";
cin>>nm;

while(display_Rec.read((char*)&rec,sizeof(rec))){
    if(strcmp(nm,rec.name)==0){
        rn=(rn-1)*sizeof(rec);
        display_Rec.seekg(rn);
        cout<<rec.mark<<"\t"<<rec.name<<"\t"<<rec.city<<endl;

        display_Rec.close();
        t=1;
    }
rn++;
}
if(t==0)
cout<<"Record not found"<<endl;
}


void person::delrec(){
data rec;
char nm[15];
long int rn=0,t=0;

fstream del("employee.dat",ios::in|ios::out);
if(!del){

    cerr<<"File opening error"<<endl;
    exit(1);
}

cout<<"Enter Name of person";
cin>>nm;

while(del.read((char*)&rec,sizeof(rec))){
    if(strcmp(nm,rec.name)==0){
        cout<<"Record is : "<<rec.mark<<"\t"<<rec.name<<"\t"<<rec.city<<endl;

        if(rec.mark='*'){
            cout<<"Record already Marked \n";
            t=1;
        }
        else
        {
            rn=(rn)*sizeof(rec);
            del.seekp(rn);
            rec.mark='*';
            del.write((char*)&rec,sizeof(rec));

            cout<<"\n\n Record is marked for deletion \n";
            del.close();
            t=1;
        }
rn++;
    }
if(t==0)
    cout<<"Record not found";

}
}

void person::pack(void){
data rec;
char nm[15];
long int rn=0;

ifstream pack_Rec("employee.dat",ios::binary);
ofstream pack_Rec_open("temp.dat",ios::binary);

if(!pack_Rec){
    cerr<<"File opening error";
    exit(1);
}

while(pack_Rec.read((char*)&rec,sizeof(rec))){

    if(rec.mark!='*')
        pack_Rec_open.write((char*)&rec,sizeof(rec));
        rn++;
}
pack_Rec_open.close();
pack_Rec.close();

remove("employee.dat");
rename("temp.dat","employee.dat");
cout<<"Records are copies";

}

add records and update records are working properly but other functions are not properly?