Thread: Need Some Help!

Accually i need to create a student database but i have a problem when i try to add a new student, it overwrites on the old student data so, when i choose display, only the last student that i have entered will appear !! ..

this is what i have done so far ...

Code:

#include <iostream>
#include <stdlib.h>
#include <fstream>

using namespace std;


void add();
void display();

struct student{
       char fname[100];
       char lname[100];
       int id;
       float cgpa;
           };
           
int main(int argc, char *argv[])
{
  int x;
  
 
 do{
  cout <<"============================\n";
  cout <<"            Menu            \n";
  cout <<"============================\n";
  cout <<endl;
  cout <<"={1}= Add a new student.\n";
  cout <<"={2}= Display all\n";
  cout <<"={3}= Exit\n";
  
  cout <<"============================\n";
  
  
  cout <<"Your Choice: ";
  cin >>x;
  
  switch (x){
  case 1 : add();break; 
  case 2 : display();break;
  case 3 : ;break;
  
  default : cout <<"Invalid Choice\n";
  }
  }while (x != 3);
  
  system("PAUSE");	
  return 0;
}



// Add a new student to the database
void add()
{
  
  student info[200];
  int i;
  
 
  
  
  cout << "Enter student's first name: ";
  cin >>info[i].fname;
  
  cout << "Enter student's second name: ";
  cin >>info[i].lname;
  
  cout <<"Enter the student id: ";
  cin >> info[i].id;
  
  cout << "Enter the student CGPA: ";
  cin >> info[i].cgpa; 
  
 
        ofstream fout;
        fout.open("datab.bin",ios::out|ios::binary);
        fout.write(reinterpret_cast<char*>(&info[i]),sizeof(info));
        fout.close();
  
  
}

void display()
{
student info[200];
int i;
 
        ifstream fin; 
        fin.open("datab.bin",ios::in|ios::binary);
        fin.read(reinterpret_cast<char*>(&info[i]),sizeof(info));
        
        fin.close();
       
        
        cout << "Name: "<<info[i].fname<<" "<<info[i].lname<<endl;
        cout << "ID: "<<info[i].id<<endl;
        cout << "CGPA: "<<info[i].cgpa<<endl;
}

It seems scary to me that you declare an array of students, index them with 'i' without ever setting 'i' to a number!

thanx guyz for the help .. but i still don't get it .. (still bigenner)

I want to save an array of structure in a binary file and then display ALL the information i have saved.
I have been sittin on this chair for 2 dayz but i couldn't solve it. can u guyz help me PLZ ..
thanX....

This is my code .. accually with this code i can only save one student data .. i want to save more than one and display them all ....

Code:

#include <iostream>
#include <stdlib.h>
#include <fstream>

using namespace std;


int add();
void display();
void save();
void load();

struct student{
       char fname[100];
       char lname[100];
       int id;
       float cgpa;
           };
           
int main(int argc, char *argv[])
{
  int x;
  
 
 do{
  cout <<"============================\n";
  cout <<"            Menu            \n";
  cout <<"============================\n";
  cout <<endl;
  cout <<"={1}= Add a new student.\n";  
  cout <<"={2}= Display all\n";
  cout <<"={3}= Save\n";
  cout <<"={4}= Load\n";
  cout <<"={5}= Exit\n";
  cout <<"============================\n";
  
  
  cout <<"Your Choice: ";
  cin >>x;
  
  switch (x){
  case 1 : add();break; 
  case 2 : display();break;
  case 3 : save();break;
  case 4 : load();break;
  case 5 : ;break;
  default : cout <<"Invalid Choice\n";
  }
  }while (x != 5);
  
  system("PAUSE");	
  return 0;
}

//=====================================================
student info[200];
int i,num;
//============================================================
// Add a new student to the database
int add()
{
    
  cout << "Enter student's first name: ";
  cin >>info[i].fname;
  
  cout << "Enter student's second name: ";
  cin >>info[i].lname;
  
  cout <<"Enter the student id: ";
  cin >> info[i].id;
  
  cout << "Enter the student CGPA: ";
  cin >> info[i].cgpa; 
  
         
}
//===============================[ display ]=======================
void display()
{
        
          
        cout << "Name: "<<info[i].fname<<" "<<info[i].lname<<endl;
        cout << "ID: "<<info[i].id<<endl;
        cout << "CGPA: "<<info[i].cgpa<<endl;

        
}
//========================[ save ]=============================
void save()
{
        ofstream fout;
        fout.open("datab.txt",ios::out|ios::binary);
        fout.write(reinterpret_cast<char*>(&info[i]),sizeof(student));
        fout.close();
        
}
//=======================[load]=================================
void load()
{
        ifstream fin; 
        fin.open("datab.txt",ios::in|ios::binary);
        fin.read(reinterpret_cast<char*>(&info),sizeof(student));       
        fin.close();        
}

sorry for interrupting but it seems youve posted the same subject 3 times but with different aproaches, why not keep it in the same thread? lol such a c++ related question...