In-Class Exercise
Overloading Constructors
This exercise overloads the no-argument constructor and simplifies
internal class logic by referring to the current object directly.
Given Information
The following code is a solution to the
Handout on Constructors and Destructors.
Client Module
// Constructors and Destructors
// h5.cpp
#include <new>
#include <iostream>
using namespace std;
#include "Transaction.h"
int main() {
int n; // user-sprecified number of Transactions
Transaction* tr;
cout << "Enter the number of Transactions : ";
cin >> n;
tr = new (nothrow) Transaction[n];
if (tr == nullptr) {
cout << "Memory Allocation Error " << endl;
return 1;
}
cout << "Enter " << n << " Transactions" << endl;
for (int i = 0; i < n; i++)
tr[i].enter();
cout << endl;
cout << " Account Description Credit Debit" << endl;
for (int i = 0; i < n; i++) {
tr[i].display();
cout << endl;
}
delete [] tr;
}
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Transaction Module
Transaction.h
// Constructor and Destructor
// Transaction.h
class Transaction {
int acct;
char type;
char desc[21];
double amount;
public:
Transaction();
~Transaction();
void enter();
void display() const;
};
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Transaction.cpp
// Constructors and Destructors
// Transaction.cpp
#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;
#include "Transaction.h"
Transaction::Transaction() {
acct = 0;
desc[0] = '\0';
type = 'd';
amount = 0.0;
}
Transaction::~Transaction() { }
void Transaction::enter() {
// local variables accept input temporarily
int acct_;
char type_;
char desc_[21];
double amount_;
// store input from the user in the local variables
cout << "Enter the account number : ";
cin >> acct_; ;
cin.ignore();
cout << "Enter the desription : ";
cin.getline(desc_, 21);
cout << "Enter the account type (d for debit, c for credit) : ";
cin >> type_; ;
cout << "Enter the account amount : ";
cin >> amount_;
if (acct_ > 0 && (type_ == 'd' || type_ == 'c') && amount_ > 0.0) {
// copy validated input into the instance variables
acct = acct_;
type = type_;
strcpy(desc, desc_);
amount = amount_;
}
else {
// input was invalid - adopt a safe empty state
acct = 0;
type = 'd';
desc[0] = '\0';
amount = 0.0;
}
}
void Transaction::display() const {
if (acct != 0) {
cout << setw(10) << acct;
cout << ' ' << setw(20) << left << desc << right;
cout << setprecision(2) << fixed;
if (type == 'd')
cout << setw(20) << amount;
else
cout << setw(10) << amount;
}
else
cout << "no data available" << endl;
}
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Your Task
Client Module
The following client program uses your upgraded Transaction module.
The dynamic memory allocation has been removed.
// Overloading Constructors
// h6.cpp
#include <iostream>
using namespace std;
#include "Transaction.h"
const int N = 3;
int main() {
Transaction tr[N];
cout << "Enter " << n << " Transactions" << endl;
for (int i = 0; i < N; i++)
tr[i].enter();
cout << endl;
cout << " Account Description Credit Debit" << endl;
for (int i = 0; i < N; i++) {
tr[i].display();
cout << endl;
}
}
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Transaction Module
Upgrade the definition of the Transaction
class to include a four-argument constructor. Make sure that
your class processes valid as well as invalid input properly.
Transaction.h
Upgrade the header file for your Transaction class:
- add the prototype for the four-argument constructor
// Overloading Constructor
// Transaction.h
class Transaction {
int acct;
char type;
char desc[21];
double amount;
public:
Transaction();
~Transaction();
void enter();
void display() const;
};
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Transaction.cpp
Upgrade the implementation file for your Transaction type:
- add the definition for the four-argument constructor
- add the logic for validating data to your four-argument constructor
- call the four-argument constructor from the enter()
function
// Overloading Constructor
// Transaction.cpp
#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;
#include "Transaction.h"
Transaction::Transaction() {
acct = 0;
desc[0] = '\0';
type = 'd';
amount = 0.0;
}
Transaction::~Transaction() { }
void Transaction::enter() {
// local variables accept input temporarily
int acct_;
char type_;
char desc_[21];
double amount_;
// store input from the user in the local variables
cout << "Enter the account number : ";
cin >> acct_; ;
cin.ignore();
cout << "Enter the desription : ";
cin.getline(desc_, 21);
cout << "Enter the account type (d for debit, c for credit) : ";
cin >> type_; ;
cout << "Enter the account amount : ";
cin >> amount_;
}
void Transaction::display() const {
if (acct != 0) {
cout << setw(10) << acct;
cout << ' ' << setw(20) << left << desc << right;
cout << setprecision(2) << fixed;
if (type == 'd')
cout << setw(20) << amount;
else
cout << setw(10) << amount;
}
else
cout << "no data available" << endl;
}
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