In-Class Exercise
Dynamic Memory
This exercise introduces dynamic memory allocation for
a user-defined number of elements. There is no limit on the
number that the user selects, except the maximum that the operating
system provides.
Given Information
The following code is a solution to the
Handout on Input and Output.
Client Module
h3.h
// Input and Output
// h3.h
#define NO_TRANSACTIONS 3
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h3.cpp
// Input and Output
// h3.cpp
#include <iostream>
using namespace std;
#include "h3.h"
#include "Transaction.h"
int main() {
Transaction tr[NO_TRANSACTIONS];
cout << "Enter " << NO_TRANSACTIONS << " Transactions" << endl;
for (int i = 0; i < NO_TRANSACTIONS; i++)
tr[i].enter();
cout << endl;
cout << " Account Description Credit Debit" << endl;
for (int i = 0; i < NO_TRANSACTIONS; i++) {
tr[i].display();
cout << endl;
}
}
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Transaction Module
Transaction.h
// Input and Output
// Transaction.h
struct Transaction {
private:
int acct;
char type;
char desc[21];
double amount;
public:
void enter();
void display() const;
};
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Transaction.cpp
// Input and Output
// Transaction.cpp
#include <iostream>
#include <iomanip>
using namespace std;
#include "Transaction.h"
void Transaction::enter() {
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 {
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;
}
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Your Task
Client Module
Upgrade the client module to accept a user-specified
number of Transactions, to accept the data for each
object in turn, and finally to display the data for each object
in tabular form:
- include the header file for dynamic memory allocation errors
- allocate space for a pointer to a single Transaction
- allocate dynamic memory for an array of Transactions that
contains the specified number of elements
- deallocate the dynamic memory before returning control to the operating system
// Dynamic Memory
// h4.cpp
#include <iostream>
using namespace std;
#include "Transaction.h"
int main() {
int n; // user-specified number of Transactions
Transaction ;
cout << "Enter the number of Transactions : ";
cin >> n;
cout << "Enter " << << " 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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