OOP244-Workshop 2 Dynamic Memory Solved

In this workshop, you allocate memory at run-time and deallocate that memory as soon as it is no longer required.

LEARNING OUTCOMES 
Upon successful completion of this workshop, you will have demonstrated the abilities to:

•        allocate and deallocate dynamic memory for an array of elements;

•        resize the amount of dynamically allocated memory;

•        overload a global function;

•        explain the difference between statically and dynamically allocated memory;  describe what you have learned in completing this workshop.

             


IN-LAB  
Design and code a structure (struct) named Kingdom in the namespace sict.  Your structure should have two data members:

m_name: a statically allocated array of characters of size 32 (including '\0') that holds the name of the kingdom;

m_population: an integer that stores the number of people living in the kingdom.

Add to the sict namespace, a function called display(...) that returns nothing, receives as a parameter an unmodifiable reference to an object of type Kingdom and prints the object to the screen in the following format:

KINGDOM_NAME, population POPULATION<ENDL 

Kingdom.h
.
Kingdom.cpp
 Store your struct definition and the display(...) declaration in a header file named Store your display(...) definition in an implementation file named . Replace the ellipsis (...) with the proper parameter as appropriate.

Complete the implementation of the w2_in_lab.cpp main module shown below (see the parts marked with TODO). You may use the read(...) function provided to accept input from the user. You do not need to write your own read(...) function. The expected output from your program is listed below the source code listing. The scarlet red color identifies what you yourself should type as input to your program. The green color identifies what is generated by your program. The output of your program should match exactly the sample output shown below.

// Workshop 2: Dynamic Memory 

// File: w2_in_lab.cpp 

// Author: Cornel 

// Date: 2019/05/06  

#include <iostream 

#include "Kingdom.h" 

#include "Kingdom.h"// intentional 

 

using namespace std; using namespace sict; 

 

void read(sict::Kingdom&); 

 

int main() { 
    int count = 0; // the number of kingdoms in the array  

    // TODO: declare the pKingdom pointer here (don't forget to initialize it) 

     cout << "==========\n"          << "Input data\n" 

         << "==========\n" 

         << "Enter the number of Kingdoms: ";     cin count;     cin.ignore(); 

 

    if (count < 1) return 1; 

 

    // TODO: allocate dynamic memory here for the pKingdom pointer 

 

    for (int i = 0; i < count; ++i) { 

        cout << "Kingdom #" << i + 1 << ": " << endl;         // TODO: add code to accept user input for Kingdom i 

    } 

    cout << "==========" << endl << endl; 

 

    // testing that "display(...)" works 

    cout << "------------------------------" << endl          << "The 2nd kingdom entered is" << endl          << "------------------------------" << endl;     sict::display(pKingdom[1]); 

    cout << "------------------------------" << endl << endl;  

    // TODO: deallocate the dynamic memory here 

 

    return 0; 

} 

 

// read accepts data for a Kingdom from standard input 

// 

void read(sict::Kingdom& kingdom) { 

 

    cout << "Enter the name of the Kingdom: ";     cin.get(kingdom.m_name, 32, '\n');     cin.ignore(2000, '\n'); 

    cout << "Enter the number of people living in " << kingdom.m_name << ": ";     cin kingdom.m_population;     cin.ignore(2000, '\n'); } 
OUTPUT SAMPLE: 

========== 

Input data 

========== 

Enter the number of Kingdoms: 2 

Kingdom #1:  

Enter the name of the Kingdom: The_Vale Enter the number of people living in The_Vale: 234567 

Kingdom #2:  

Enter the name of the Kingdom: The_Reach 

Enter the number of people living in The_Reach: 567890 

========== 

 

------------------------------ 

The 2nd kingdom entered is 

------------------------------ 

The_Reach, population 567890 ------------------------------ 

To complete your coding  

a)    remove all comments that have been included to assist you with your tasks (marked with TODO).

b)    Include in each file appropriate header comments uniquely identify the file

(as shown above)

c)     Preface each function definition in the implementation file with a function header comment explaining what the function does in a single phrase (as shown above).

AT-HOME 
Copy your header and implementation files (Kingdom.h, Kingdom.cpp) from your in-lab directory to your at-home directory. Upgrade the files in your at-home directory as follows.

Overload sict::display(...) by adding a function of the same name that returns nothing and has two parameters: the first parameter receives the address of an unmodifiable array of Kingdoms, and the second one receives an integer holding the number of elements in the array. This function calculates the total number of people living in all of the Kingdoms and prints the array information to the screen (in the reverse order) in the following format:

------------------------------<ENDL 

Kingdoms of SICT<ENDL 

------------------------------<ENDL 

3. KINGDOM_NAME, population POPULATION<ENDL 2. KINGDOM_NAME, population POPULATION<ENDL 

1. KINGDOM_NAME, population POPULATION<ENDL 

------------------------------<ENDL 

Total population of SICT: TOTAL_POPULATION<ENDL 

------------------------------<ENDL 

NOTE: this overload must be part of the sict namespace, have a declaration in Kingdom.h and an implementation in Kingdom.cpp.

NOTE: this overload must call the sict::display(...) function you created for the in-lab part in order to display the name and the population of each kingdom in the array of kingdoms.
Complete the w2_at_home.cpp implementation file of the main module (see the parts in the source code listed below and marked with TODO; reuse the parts that you have completed for the in-lab part).  

Your tasks include expanding the amount of dynamic memory allocated for the array of Kingdoms by one element after reading the original input, and then reading the data for the new element as shown below. The test input and the expected output from your program are listed below this source code (the input to your program is shown in red). The output of your program should match exactly the sample output shown below.

// Workshop 2: Dynamic Memory 

// File: w2_at_home.cpp 

// Author: Cornel 

// Date: 2019/05/06 

 

#include <iostream 

#include "Kingdom.h" 

#include "Kingdom.h"// intentional 

 using namespace std; using namespace sict; 

 

void read(sict::Kingdom&); 

 

int main() { 

    int count = 0; // the number of kingdoms in the array  

    // TODO: declare the pKingdom pointer here (don't forget to initialize it) 

     cout << "==========\n"          << "Input data\n" 

         << "==========\n" 

         << "Enter the number of Kingdoms: ";     cin count;     cin.ignore(); 

 

    if (count < 1) return 1; 

 

    // TODO: allocate dynamic memory here for the pKingdom pointer 

 

    for (int i = 0; i < count; ++i) { 

        cout << "Kingdom #" << i + 1 << ": " << endl;         // TODO: add code to accept user input for Kingdom i 

    } 

    cout << "==========" << endl << endl; 

 

    // testing that "display(...)" works 

    cout << "------------------------------" << endl          << "The 1st kingdom entered is" << endl          << "------------------------------" << endl;     display(pKingdom[0]); 

    cout << "------------------------------" << endl << endl;  

    // expand the array of Kingdoms by 1 element 

    { 

        // TODO: allocate dynamic memory for count + 1 Kingdoms 

        // TODO: copy elements from original array into this newly allocated array 

        // TODO: deallocate the dynamic memory for the original array 
 

 

 

        // TODO: copy the address of the newly allocated array into pKingdom pointer 

        // add the new Kingdom         cout << "==========\n"              << "Input data\n" 

             << "==========\n" 

             << "Kingdom #" << count + 1 << ": " << endl;         // TODO: accept input for the new element in the array         count++; 

        cout << "==========\n" << endl;     } 

    // testing that the overload of "display(...)" works     display(pKingdom, count); 

    // TODO: deallocate the dynamic memory here 

    return 0;  

// read accepts data for a Kingdom from standard input 

// 

void read(Kingdom& kingdom) { 

    cout << "Enter the name of the Kingdom: ";     cin.get(kingdom.m_name, 32, '\n');     cin.ignore(2000, '\n'); 

    cout << "Enter the number of people living in " << kingdom.m_name << ": ";     cin kingdom.m_population;     cin.ignore(2000, '\n');  
}

 

}

OUTPUT SAMPLE: 

========== 

Input data 

========== 

Enter the number of Kingdoms: 2 

Kingdom #1: 

Enter the name of the Kingdom: The_Vale Enter the number of people living in The_Vale: 234567 

Kingdom #2: 

Enter the name of the Kingdom: The_Reach 

Enter the number of people living in The_Reach: 567890 

========== 

 

------------------------------ 

The 1st Kingdom entered is 

------------------------------ 

The_Vale, population 234567 

------------------------------ 

 

========== 

Input data 

========== Kingdom #3: 

Enter the name of the Kingdom: The_Riverlands 

Enter the number of people living in The_Riverlands: 123456 

========== 

 

------------------------------ Kingdoms of SICT 

------------------------------ 

3. The_Riverlands, population 123456 

2. The_Reach, population 567890 

1. The_Vale, population 234567 ------------------------------ 

Total population of SICT: 925913 

------------------------------ 
To complete your coding  

a)    remove all comments that have been included to assist you with your tasks (marked with TODO).

b)    Include in each file appropriate header comments that uniquely identify the file (as shown above)

c)     Preface each function definition in the implementation file with a function header comment explaining what the function does in a single phrase (as shown above).

REFLECTION  
Study your final solution, reread the related parts of the course notes, and make sure that you have understood the concepts covered by this workshop

Create a file named reflect.txt that contains your detailed description of the topics that you have learned in completing this workshop and mention any issues that caused you difficulty. Include in your explanation—but do not limit it to—the following points:

1)      Why do you need to allocate new dynamic memory when you increase the size of an existing array of dynamically allocated memory?

2)      The Kingdom structure stores the name of the kingdom in an array of characters. At the end of the program, we do not use the delete operator to deallocate the memory occupied by the name itself. Why don’t we need to use the delete e operator on this array itself?  

3)      There are two display(...) function definitions. How does the compiler know which definition to call from your main function?  4) Describe what have you have learned in this workshop.