writing data to a file from an array of pointers

**Mingzhi** · 07-19-2004

Firstly, I apologized to all who are going to read my program. There are not comments and it is a long one. Anyway, I have a problem trying to write the data pointed to by Employee * STAFF[20] to a file named employee.dat. It writes the address
pointed to my STAFF instead. Anyway here is the code

// the driver file

Code:

#include <fstream>
#include <iomanip>
#include <cstdlib>
#include "employee.h"
using namespace std;

int main()
{

	Direct D1("Harry Johnson", 25,45365,800,10), D2;
	Indirect ID3("Larry King", 60, 34546,20,40), ID4;

	Employee *STAFF[20]; cin>>D2; cin>>ID4; system("cls"); 
	STAFF[0]=&D1; STAFF[1]=&D2;
	STAFF[2]=&ID3; STAFF[3]=&ID4;

	int count=4;

	ifstream direct; ifstream indirect;
	direct.open("direct.dat", ios::in);
	if(direct.fail())
	{
		cerr<<"direct.dat cannot be opened\n";
		exit(1);
	}
	indirect.open("indirect.dat", ios::in);
	if(indirect.fail())
	{
		cerr<<"indirect.dat cannot be opened\n";
		exit(1);
	}

	while(!direct.eof())
	{
		Direct *temp=new Direct;
		direct>>*temp;
		STAFF[count]=temp;
		count++;
	}

	direct.close();
	count--;

	while(!indirect.eof())
	{
		Indirect *temp=new Indirect;
		indirect>>*temp;
		STAFF[count]=temp;
		count++;
	}

	indirect.close();
	count--;

	cout<<"Type"<<setw(11)<<"Name"<<setw(22)<<"Age"<<setw(5)<<"Id"<<setw(17)<<"Basic/Hours"
		<<setw(11)<<"Cpf/Rate"<<setw(6)<<"Pay"<<endl;
	cout<<"======================================================"
		<<"======================\n";
	
	for(int loop=0; loop<4; loop++)
	{
		STAFF[loop]->cal_pay();
		STAFF[loop]->display();
	}

	for(loop=4; loop<count;loop++)
	{
		if(loop%8==0)
		{
			cout<<endl; system("pause"); system("cls");
			cout<<"Type"<<setw(11)<<"Name"<<setw(22)<<"Age"<<setw(5)<<"Id"<<setw(17)<<"Basic/Hours"
		        <<setw(11)<<"Cpf/Rate"<<setw(6)<<"Pay"<<endl;

			cout<<"======================================================"
				<<"======================\n";
	
		}
		STAFF[loop]->cal_pay();
		STAFF[loop]->display();
	}

	system("pause"); system("cls");

	for(loop=1; loop<count; loop++)
	{
		for(int number=0; number<count-1; number++)
		{
			if(strcmp(STAFF[number]->getname(), 
				STAFF[number+1]->getname())>0)
			{
				Employee *temp=STAFF[number];
				STAFF[number]=STAFF[number+1];
				STAFF[number+1]=temp;
			}
			
		}
	}

	cout<<"Type"<<setw(11)<<"Name"<<setw(22)<<"Age"<<setw(5)<<"Id"<<setw(17)<<"Basic/Hours"
		<<setw(11)<<"Cpf/Rate"<<setw(6)<<"Pay"<<endl;

	cout<<"======================================================"
		<<"======================\n";
	

	for(loop=0; loop<count; loop++)
	{
		STAFF[loop]->display();
	}

	ofstream employee; employee.open("employee.dat", ios::out);
	if(employee.fail())
	{
		cerr<<"employee.dat cannot be opened\n";
		exit(1);
	}

	employee<<"Type"<<setw(11)<<"Name"<<setw(22)<<"Age"<<setw(5)<<"Id"<<setw(17)<<"Basic/Hours"
		<<setw(11)<<"Cpf/Rate"<<setw(6)<<"Pay"<<endl;

	employee<<"======================================================"
		<<"======================\n";

	for(loop=0; loop<count; loop++)
	{
                // how to solve this?
		employee<<STAFF[loop]<<endl;
	}

	cout<<endl;
	return 0;
}

// the employee.h

#include <iostream>
using namespace std;

#ifndef _EMPLOYEE_H_
#define _EMPLOYEE_H_

class Employee
{
 protected:
	char name[20]; float age; int EID; float pay;
public:

	Employee();
	Employee(char *name, float ag, int ID, float p);
	char *getname();
	virtual void cal_pay()=0;
	virtual void display()=0;
	
};

class Direct:public Employee
{
	float basic; float cpf_rate;
public:
	Direct();
	Direct(char *name, float ag, int ID, float bas, float rat);
	void cal_pay();
	void display();
	void read_keyboard(istream & input);
	void read_file(ifstream & input);
	void write_file(ofstream & output);
	
};

istream & operator>>(istream & input, Direct & person);
ifstream & operator>>(ifstream & input, Direct & person);
ofstream & operator<<(ofstream & output, Direct & person);

class Indirect:public Employee
{
	float hours; float rate;
public:
	Indirect();
	Indirect(char *name, float ag, int ID, float hrs, float rat);
	void cal_pay();
	void display();
	void read_keyboard(istream & input);
	void read_file(ifstream & input);
	void write_file(ofstream & output);
};

istream & operator>>(istream & input, Indirect & person);
ifstream & operator>>(ifstream & input, Indirect & person);
ofstream & operator<<(ofstream & output, Indirect & person);

#endif

// the employee.cpp

#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include "employee.h"

using namespace std;

Employee::Employee()
{
	pay=0;
}

Employee::Employee(char *nam, float ag, int ID, float p)
{
	strcpy(name,nam); age=ag; EID=ID; pay=p; 
}

char *Employee::getname() 
{
	return name;
}

void Employee::cal_pay()
{

}

void Employee::display()
{

}

////////////////////////////////////////////////////////////////

Direct::Direct()
{
	basic=0;
	cpf_rate=0;
}

Direct::Direct(char *nam, float ag, int ID, float bas, float rat)
{
	strcpy(name,nam); age=ag; EID=ID;
	basic=bas;
	cpf_rate=rat;
}

void Direct::cal_pay()
{
	pay=basic*(1-(cpf_rate/100));
}

void Direct::display()
{
    int length=strlen(name);
	cout<<"Direct"<<setw(5+length)<<name;

	char number[10];
	length=23-length+strlen(itoa(age,number,10));
	cout<<setw(length)<<age<<setw(9)<<EID; length=3+strlen(itoa(basic,number,10));
	cout<<setw(length)<<basic; length=14-strlen(itoa(basic,number,10))
										+strlen(itoa(cpf_rate,number,10));
	cout<<setw(length)<<cpf_rate;   length=11-strlen(itoa(cpf_rate,number,10))
									  +strlen(itoa(pay,number,10));
	cout<<setw(length)<<pay<<endl;
    
}

void Direct::read_keyboard(istream & input)
{
	cout<<"Please enter the name of the employee\n";
	input.getline(name,255,'\n');
	cout<<"Please enter the age of the employee\n";
	input>>age;
	cout<<"Please enter the id of the employee\n";
	input>>EID;
	cout<<"Please enter the basic pay of the employee\n";
	input>>basic;
	cout<<"Please enter the cpf rate of the employee\n";
	input>>cpf_rate;
	cin.ignore(255,'\n');
}

void Direct::read_file(ifstream & input)
{
	input.getline(name,255,'*'); 
	input>>age>>EID>>basic>>cpf_rate; input.ignore(255,'\n'); 
}

void Direct::write_file(ofstream & output)
{
	int length=strlen(name);
	output<<"Direct"<<setw(5+length)<<name;

	char number[10];
	length=23-length+strlen(itoa(age,number,10));
	output<<setw(length)<<age<<setw(9)<<EID; length=3+strlen(itoa(basic,number,10));
	output<<setw(length)<<basic; length=14-strlen(itoa(basic,number,10))
										+strlen(itoa(cpf_rate,number,10));
	output<<setw(length)<<cpf_rate;   length=11-strlen(itoa(cpf_rate,number,10))
									  +strlen(itoa(pay,number,10));
	output<<setw(length)<<pay<<endl;
	
}

istream & operator>>(istream & input, Direct & person)
{
	person.read_keyboard(input);
	return input;
}

ifstream & operator>>(ifstream & input, Direct & person)
{
	person.read_file(input);
	return input;
}

ofstream & operator<<(ofstream & output, Direct & person)
{
	person.write_file(output);
	return output;
}

/////////////////////////////////////////////////////////////////

Indirect::Indirect()
{
	hours=0;
	rate=0;
}

Indirect::Indirect(char *nam, float ag, int ID, float hrs, 
				   float rat)
{
	strcpy(name,nam); age=ag; EID=ID;
	hours=hrs;
	rate=rat;
}

void Indirect::cal_pay()
{
	if(hours>40)
	{
		int extra_hours=hours-40;
		pay=40*rate+extra_hours*1.5*rate;
	}

	else
		pay=hours*rate;
}

void Indirect::display()
{
	int length=strlen(name); char number[10];  length=length+3;
	cout<<"Indirect"<<setw(length)<<name; length=23-strlen(name)
		                                         +strlen(itoa(age,number,10)); 
	cout<<setw(length)<<age;
	cout<<setw(9)<<EID; length=3+strlen(itoa(hours,number,10));
	cout<<setw(length)<<hours; length=14-strlen(itoa(hours,number,10))
									  +strlen(itoa(rate,number,10));
	cout<<setw(length)<<rate; length=11-strlen(itoa(rate,number,10))
		                             +strlen(itoa(pay,number,10));
	cout<<setw(length)<<pay<<endl;
}

void Indirect::read_keyboard(istream & input)
{
	cout<<"Please enter the name of the employee\n";
	input.getline(name,255,'\n');
	cout<<"Please enter the age of the employee\n";
	input>>age;
	cout<<"Please enter the id of the employee\n";
	input>>EID;
	cout<<"Please enter the number of hours worked for the employee\n";
	input>>hours;
	cout<<"Please enter the rate of the employee\n";
	input>>rate;
	cin.ignore(255,'\n');
}

void Indirect::read_file(ifstream & input)
{
	input.getline(name,255,'*'); input>>age>>EID
		>>hours>>rate; input.ignore(1,EOF);
	
}

void Indirect::write_file(ofstream & output)
{
	int length=strlen(name); char number[10];  length=length+3;
	cout<<"Indirect"<<setw(length)<<name; length=23-strlen(name)
		                                         +strlen(itoa(age,number,10)); 
	cout<<setw(length)<<age;
	cout<<setw(9)<<EID; length=3+strlen(itoa(hours,number,10));
	cout<<setw(length)<<hours; length=14-strlen(itoa(hours,number,10))
									  +strlen(itoa(rate,number,10));
	cout<<setw(length)<<rate; length=11-strlen(itoa(rate,number,10))
		                             +strlen(itoa(pay,number,10));
	cout<<setw(length)<<pay<<endl;
	
}

istream & operator>>(istream & input, Indirect & person)
{
	person.read_keyboard(input);
	return input;
}

ifstream & operator>>(ifstream & input, Indirect & person)
{
	person.read_file(input);
	return input;
}

ofstream & operator<<(ofstream & output, Indirect & person)
{
	person.write_file(output);
	return output;
}

Here is the output of employee.dat

Type Name Age Id Basic/Hours Cpf/Rate Pay
================================================== ==========================
004A42F0
0012FF1C
004A4410
004A33A0
004A3340
004A34F0
004A4350
004A41D0
0012FF48
004A4290
0012FEF0
0012FEC4
004A4230

**kuphryn** · 07-19-2004

In the follow code you want to copy the string from classes Direct and Indirect to class STAFF, correct?

STAFF[0]=&D1;
STAFF[1]=&D2;
STAFF[2]=&ID3;
STAFF[3]=&ID4;

You are assigning each element of STAFF array the address of the first element of the other instantiations. One solution is strcpy(). Another solution is memcpy().

Kuphryn

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