please include a class diagram.

Change the database.cpp program to throw exceptions when there is an unexpected problem. When appropriate offer the user an option to fix the problem.

Database.cpp---------------------------

#include

#include

#include

#include

using namespace std;

#include "ccc_empl.h"

const int NEWLINE_LENGTH = 2;

const int RECORD_SIZE = 30 + 10 + NEWLINE_LENGTH;

/**

Converts a string to a floating-point value, e.g.

"3.14" -> 3.14.

@param s a string representing a floating-point value

@return the equivalent floating-point value

*/

double string_to_double(string s)

{

istringstream instr(s);

double x;

instr >> x;

return x;

}

/**

Raises an employee salary.

@param e employee receiving raise

@param percent the percentage of the raise

*/

void raise_salary(Employee& e, double percent)

{

double new_salary = e.get_salary() * (1 + percent / 100);

e.set_salary(new_salary);

}

/**

Reads an employee record from a file.

@param e filled with the employee

@param in the stream to read from

*/

void read_employee(Employee& e, istream& in)

{

string line;

getline(in, line);

if (in.fail()) return;

string name = line.substr(0, 30);

double salary = string_to_double(line.substr(30, 10));

e = Employee(name, salary);

}

/**

Writes an employee record to a stream.

@param e the employee record to write

@param out the stream to write to

*/

void write_employee(Employee e, ostream& out)

{

out << e.get_name()

<< setw(10 + (30 - e.get_name().length()))

<< fixed << setprecision(2)

<< e.get_salary();

}

int main()

{

cout << "Please enter the data file name: ";

string filename;

cin >> filename;

fstream fs;

fs.open(filename.c_str());

fs.seekg(0, ios::end); // Go to end of file

int nrecord = fs.tellg() / RECORD_SIZE;

cout << "Please enter the record to update: (0 - "

<< nrecord - 1 << ") ";

int pos;

cin >> pos;

const double SALARY_CHANGE = 5.0;

Employee e;

fs.seekg(pos * RECORD_SIZE, ios::beg);

read_employee(e, fs);

raise_salary(e, SALARY_CHANGE);

cout << "New salary: " << e.get_salary();

fs.seekp(pos * RECORD_SIZE, ios::beg);

write_employee(e, fs);

fs.close();

return 0;

}

Ccc_empl.h--------------------------------

#ifndef CCC_EMPL_H

#define CCC_EMPL_H

#include

using namespace std;

/**

A basic employee class that is used in many examples

in the book "Computing Concepts with C++ Essentials"

*/

class Employee

{

public:

/**

Constructs an employee with empty name and no salary.

*/

Employee();

/**

Constructs an employee with a given name and salary.

@param employee_name the employee name

@param initial_salary the initial salary

*/

Employee(string employee_name, double initial_salary);

/**

Sets the salary of this employee.

@param new_salary the new salary value

*/

void set_salary(double new_salary);

/**

Gets the salary of this employee.

@return the current salary

*/

double get_salary() const;

/**

Gets the name of this employee.

@return the employee name

*/

string get_name() const;

private:

string name;

double salary;

};

#endif

Ccc_empl.cpp------------------------------

#include "ccc_empl.h"

Employee::Employee()

{

salary = 0;

}

Employee::Employee(string employee_name, double initial_salary)

{

name = employee_name;

salary = initial_salary;

}

void Employee::set_salary(double new_salary)

{

salary = new_salary;

}

double Employee::get_salary() const

{

return salary;

}

string Employee::get_name() const

{

return name;

}