Question

Assignment

Write a menu-driven C++ program to manage a class roster of student names that can grow and shrink dynamically. It should work something like this (user input highlighted in blue):

Array size: 0, capacity: 2
MENU
A Add a student
D Delete a student
L List all students
Q Quit
...your choice: a[ENTER]

Enter the student name to add: Jonas-Gunnar Iversen[ENTER]

Array size: 1, capacity: 2
MENU
A Add a student
D Delete a student
L List all students
Q Quit
...your choice: a[ENTER]

Enter the student name to add: Marcela Nogueira[ENTER]

Array size: 2, capacity: 2
MENU
A Add a student
D Delete a student
L List all students
Q Quit
...your choice: l[ENTER]

Student Roster
--------------
Jonas-Gunnar Iversen
Marcela Nogueira

Array size: 2, capacity: 2
MENU
A Add a student
D Delete a student
L List all students
Q Quit
...your choice: d[ENTER]
Enter the student name to delete: Jonas-Gunnar Iversen[ENTER]

Array size: 1, capacity: 2
MENU
A Add a student
D Delete a student
L List all students
Q Quit
...your choice: q[ENTER]

Requirements

1. Allow the menu options to be entered in either lower or upper case.
2. Implement all the actions in the above menu -- add, delete and list.
3. Use a dynamic array of strings to store the roster, with an initial capacity of 2.
4. Double the array capacity when (a) you have a new student to add, and (b) size equals capacity. You do not need to shrink the array after deletes.
5. The output table should have a column heading as shown above.
6. Output the array size and capacity along with the output table.

Hints

You don't have to write functions for everything. You may just write code blocks in main, and if it makes sense for youto move any of them out of main and into functions (like a void function to cout a table of names), do so.

Would the operations be best handled with a series of if/else statements, or a case/switch statement?

There are some built-in string functions that convert to upper and lower case.

What to Submit

Submit your .cpp file and a screenshot of one run of the program that includes at least an "add" of a name and one "list" operation.

Answer 1

Note: The language used is C++.

Code:

#include<bits/stdc++.h>
using namespace std;

//This function will list out all the students in the array.
void listStudents(string *arr, int arraySize){
   cout<<"Student Roster\n";
   cout<<"---------------\n";
   for(int i=0;i<arraySize;i++)
       cout<<arr[i]<<"\n";
}

//This function adds a student to the string array.
//References of arr, capacity and arraySize are passed so that changes are also reflected in main function.
void addStudent(string* &arr, int & capacity, int & arraySize, string name){
  
   //If array is full, double its capacity.
   if(arraySize == capacity){
      
       //Double the capacity.
       capacity *= 2;
      
       //Create a temp pointer and point it to arr.
       string *temp = arr;
      
       //Now allocate arr with new array of increased capacity.
       arr = new string[capacity];
      
       //Copy the content of temp to arr.
       for(int i=0;i<arraySize;i++)
           arr[i] = temp[i];
      
       //Delete temp.
       delete[] temp;
   }
  
   //Add the student at the end.
   arr[arraySize] = name;
   arraySize++;
}

//This function deletes a student from the array.
void deleteStudent(string *arr, int & arraySize, string name){
   //index will store the index of student to be deleted.
   int index = arraySize;
   for(int i=0;i<arraySize;i++){
       if(arr[i] == name){
           index = i;
           break;
       }
   }
   //Just shift every element to its left after the index.
   for(int i=index+1;i<arraySize;i++){
       arr[i-1] = arr[i];
   }
   //Decrease the array size.
   arraySize--;
}

int main(){
   //Initialize capacity with 2.
   int capacity = 2;
  
   //Create a dynamic array of size = capacity.
   string *arr = new string[capacity];
  
   //Initialize array size with 0.
   int arraySize = 0;

   char option;
  
   //Menu driven program begins here.
   while(true){
      
       //Prompt the user for input.
       cout<<"Array size: "<<arraySize<<", Capacity: "<<capacity<<"\n";
       cout<<"A - Add a student\n";
       cout<<"D - Delete a student\n";
       cout<<"L - List all students\n";
       cout<<"Q - Quit\n";
       cout<<"Enter your choice: ";
       cin>>option;
      
       //Change the option to upper case letter using ASCII conversion.
       if(option >= 'a' && option <= 'z')
           option -= 32;
  
       string name;
       //cin.ignore() is used to clear input buffer.
       cin.ignore();
      
       switch(option){
          
           case 'A':
               cout<<"Enter the student name to add: ";
               getline(cin, name);
               //Add the student to the array.
               addStudent(arr, capacity, arraySize, name);
               break;
          
           case 'D':
               cout<<"Enter the student name to delete: ";
               getline(cin, name);
               //Delete the student from the list.
               deleteStudent(arr, arraySize, name);
               break;
          
           case 'L':
               //List all the students present in the array.
               listStudents(arr, arraySize);
               break;
          
           case 'Q':
               //End the program.
               return 0;
          
           default:
               //It is an invalid input.
               cout<<"Enter correct choice\n";
               break;
       }
   }
   return 0;
}

Code Snippets:

Sample Output: