C++ ERROR - Crashes upon compilation

[Vinno]

Please help me I did a program on participating in quiz competition.
Upon compilation the program crashes.
The source code:



#include<fstream.h>
#include<string.h>
#include<conio.h>
#include<stdio.h>
#include<stdlib.h>
int no=1;
class quizz
{
public:
char question[20];
char answer[10];
void get()
{
cout<<"Enter the question"<<endl;
gets(question);
cout<<"Enter the answer"<<endl;
gets(answer);
}
};

class participant
{
char name[10];
int sno;
public:
int score;

void add()
{
sno=no++;
cout<<"Enter your name :"<<endl;
gets(name);
score=0;
}

void show()
{
cout<<sno<<" "<<name<<"\t"<<"\t"<<score<<endl;
}

void calc(float s)
{
score=s;
}

int retsno()
{
return sno;
}

char* retname()
{
return name;
}
};

void main()
{
clrscr();
char ch='Y'; int choice;
while(ch=='Y'||ch=='y')
{
cout<<"Press 1 to Enroll for quiz."<<endl;
cout<<"Press 2 to take up the quiz"<<endl;
cout<<"Press 3 to input a question into database";<<endl;
cout<<"Press 4 to exit"<<endl;
cin>>choice;

switch(choice)
{
case 1:
{
product p; fstream f;
f.open("list.dat",ios::out|ios::ate|ios::binary);
p.add();
f.write((char*)&p,sizeof(p));
cout<<"Your are enrolled succesfully."<<endl;
cout<<"Your participant number is "<<p.sno;
f.close();
break;
}
case 2:
{
participant p;quizz q; char na[25];float s=0;
fstream f,f1;char ques[30],ans[10];int n,flag=0;
f.open("quiz.dat",ios::in|ios::binary);
f1.open("participant.dat",ios::in|ios::binary);
cout<<"Enter your participant number ! "; cin>>n;
cout<<"Enter your name ! "; gets(na);
while(!f.eof())
{
f1.read((char*)&p,sizeof(p));
if(strcmp(na,p.retname();)==0)&&p.sno==n)
{
flag=1;
break;
}
}
f1.close();
if(flag==1)
{
cout<<"Quiz has begun."<<endl<<"1. For every correct answer you will get 4 marks"<<endl;
cout<<"2. For every incorrect answer you will lose 1 mark"<<endl;
cout<<"Please answer the following questions."<<endl;
for(i=0;i<n;i++)
{
f.read((char*)&q,sizeof(q));
cout<<q.question<<endl;
gets(ans);
if(strcmp(q.answer,ans)==0)
s+=4;
else
s-=1;
}
f.close();
p.calc(s);
f1.open("participant.dat",ios::in|ios::out|ios::binary);
while(!f.eof())
{
f1.read((char*)&q,sizeof(q));
if(strcmp(q.retname();,p.retname();)==0)&&q.sno==p.sno)
{
seekg(-sizeof(p),ios::cur);
f1.write((char*)&p,sizeof(p));
break;
}
}
f1.close();
break;
}
case 3:
{char ch;
do
{
fstream f;quizz q;
f.open("quiz.dat",ios::app|ios::binary);
q.get;
f.write((char*)&q,sizeof(q));
f.close();
cout<<"Do you want to input more questions ? (Y/N)";
cin>>ch;
}
while(ch=="y"||ch=="Y")
break;
}
case 4:
{
exit(0);
}
default:
break;
}
cout<<"Do you want to try again ? (Y/N)";
cin>>ch;
}
}

[salem c]

You need to throw away your book and your compiler.
Whatever it is, it's been obsolete for at least 20 years.

> if(strcmp(na,p.retname();)==0)&&p.sno==n)
What's that ; right after retname() ?
Not to mention the unbalanced ( )

You're also missing a final closing brace for main as well.

> Upon compilation the program crashes.
Probably because most online quizzes use modern compilers which expect a better class of program.

Watch the //!! comments

//!! The modern style would be #include <fstream>
#include<fstream.h>
//!! The modern sytle for C header files is to drop the .h and prefix
//!! the name with c.  So string.h becomes cstring, stdio.h becomes cstdio
#include<string.h>
#include<conio.h>   //!! remove this, it's a DOS anachronism from years gone by
#include<stdio.h>
#include<stdlib.h>
int no = 1;

class quizz {
public:
  //!! why are these public?
  char question[20];
  char answer[10];
  void get() {
    cout << "Enter the question" << endl;
    //!! NEVER EVER USE gets()
    //!! There is NO protection at all against buffer overflow
    gets(question);
    cout << "Enter the answer" << endl;
    gets(answer);   //!! see above
  }
};

class participant {
  char name[10];
  int sno;
public:
  //!! why is this public?
  int score;

  void add() {
    sno = no++;
    cout << "Enter your name :" << endl;
    gets(name);   //!! see above
    score = 0;
  }
  void show() {
    cout << sno << " " << name << "\t" << "\t" << score << endl;
  }
  void calc(float s) {
    score = s;
  }
  int retsno() {
    return sno;
  }
  char *retname() {
    return name;
  }
};

//!! main returns an int.
//!! modern compilers tend to enforce this
void main()
{
  clrscr(); //!! not appropriate for online competitions
  char ch = 'Y';
  int choice;
  while (ch == 'Y' || ch == 'y') {
    cout << "Press 1 to Enroll for quiz." << endl;
    cout << "Press 2 to take up the quiz" << endl;
    cout << "Press 3 to input a question into database";
    <<endl;
    cout << "Press 4 to exit" << endl;
    cin >> choice;

    switch (choice) {
    case 1:
      {
        product p;  //!! where is this declared (oh, you meant participant)
        fstream f;
        f.open("list.dat", ios::out | ios::ate | ios::binary);
        p.add();
        f.write((char *) &p, sizeof(p));
        cout << "Your are enrolled succesfully." << endl;
        cout << "Your participant number is " << p.sno; //!! .sno is not public
        f.close();
        break;
      }
    case 2:
      {
        participant p;
        quizz q;
        char na[25];
        float s = 0;
        fstream f, f1;
        char ques[30], ans[10];
        int n, flag = 0;
        f.open("quiz.dat", ios::in | ios::binary);
        f1.open("participant.dat", ios::in | ios::binary);
        cout << "Enter your participant number ! ";
        cin >> n;
        cout << "Enter your name ! ";
        gets(na);   //!! see above
        while (!f.eof()) {
          f1.read((char *) &p, sizeof(p));
          if (strcmp(na, p.retname()) == 0 && p.sno == n) {
            flag = 1;
            break;
          }
        }
        f1.close();
        if (flag == 1) {
          cout << "Quiz has begun." << endl <<
              "1. For every correct answer you will get 4 marks" << endl;
          cout << "2. For every incorrect answer you will lose 1 mark" << endl;
          cout << "Please answer the following questions." << endl;
          for (i = 0; i < n; i++) {
            f.read((char *) &q, sizeof(q));
            cout << q.question << endl;
            gets(ans);   //!! see above
            if (strcmp(q.answer, ans) == 0)
              s += 4;
            else
              s -= 1;
          }
          f.close();
          p.calc(s);
          f1.open("participant.dat", ios::in | ios::out | ios::binary);
          while (!f.eof()) {
            f1.read((char *) &q, sizeof(q));
            if (strcmp(q.retname();, p.retname()) == 0 && q.sno == p.sno) {
              seekg(-sizeof(p), ios::cur);
              f1.write((char *) &p, sizeof(p));
              break;
            }
          }
          f1.close();
          break;
        }
    case 3:
        {
          char ch;
          do {
            fstream f;
            quizz q;
            f.open("quiz.dat", ios::app | ios::binary);
            q.get;
            f.write((char *) &q, sizeof(q));
            f.close();
            cout << "Do you want to input more questions ? (Y/N)";
            cin >> ch;
          }
          while (ch == "y" || ch == "Y")
          break;
        }
    case 4:
        {
          exit(0);
        }
    default:
        break;
      }
      cout << "Do you want to try again ? (Y/N)";
      cin >> ch;
    }
  }
}

There's more to fix beyond those.