Question

CSCI 3000 Homework 4

In this assignment, you will implement a simple version of Computer Lab administration system in C++. Your program will monitor computers in 4 computer labs and will allow users to log in and log out. Each computer lab has different number of computers.

·      Lab 1 has 10 computers

·      Lab 2 has 6 computers

·      Lab 3 has 3 computers

·      Lab 4 has 12 computers

Here is a sample state of the system:

Lab Array

Some of the computers are free (no one logged in), and some others are occupied by students.

In the implementation, you will define a Lab array (an array of string pointers) in the stack memory. This pointer array can be local to the main function or it can be a global. And each pointer in the array will point to a string array that is dynamically allocated from the heap memory. (Size of each array is given above)

Initially, all computers in all labs will be set to “Free” state. Then you will provide a menu to the user such as

1)    Print the current status of computers in all labs

2)    Log in a new student to a computer in a lab

a.     Ask user name, the lab number, and the computer number. If it is available, log that student in.

3)    Log out a student from his/her computer in a lab

a.     Ask user the lab number and the computer number. If the computer is occupied, log that student out.

4)    Exit

5)    (Bonus Option +20 Points) Add N new computers to a lab.

Note: Here you will ask user the lab number and the how many new computers (N) to add. Then you will add those computers to the lab without losing the current content (logged in students).

(Tip: You will allocate a new array space (with N more elements) from the heap, then move the content of the old array to the new array. Finally, you will send the address of the new array to corresponding lab pointer. All new elements (computers) will be set to “Free” state.

 

 

Example Case for Menu option 2:

If the current state of the labs as given in first figure, and if a new student “Kim” wants to login computer 3 of Lab 3, you will update the corresponding element in the correct array by writing students name. The new state of the labs will be

Another example would be logging out a student from the computers. In that case, the student name will be replaced with the word “Free” in the array.

 

On the top of your source code, please add your name and number, Course ID, HW number and the date using a comment block. Please see the example below,

/*

Your Name – Your number

CSCI 3000, HW-X

(Due Date)

*/

Please do not copy your code from someone else’s program. The instructor may use a code comparison program that automatically checks the similarity between different programs. And do not hesitate to contact me if you are having trouble with the homework. I will be more than happy t

Answer 1

#include <iostream>

#include <string>

#include <iomanip>

using namespace std;

 

// function declaration

int menu();

void printLabs(string *labs[], int computerInLabs[], int numLabs);

 

int main() {

 

const int numLabs = 4; // number of labs in the computer

string *labs[4]; // create an array of string pointers of size 4

int computerInLabs[] = {10,6,3,12}; // specify the current number of computers in each of the 4 labs

int choice, labNumber, computerNumber,i;

string name;

 

// allocate the computers in the labs and initialize all to Free state

for(int i=0;i<numLabs;i++)

{

labs[i] = new string[computerInLabs[i]];

for(int j=0;j<computerInLabs[i];j++)

labs[i][j] = "Free";

}

 

// loop that continues till the user exits

do

{

// input of choice

choice = menu();

 

// perform the operation based on the choice

switch(choice)

{

case 1: // display the status of lab computers

printLabs(labs,computerInLabs,numLabs);

break;

 

case 2: // log in a new student to a computer in a lab

// input the name of the student

cout<<"Enter name : ";

cin>>name;

// input the lab number

cout<<"Enter the lab number(1-"<<numLabs<<") : ";

cin>>labNumber;

// validate the labNumber, if invalid re-prompt until valid

while(labNumber < 1 || labNumber > numLabs)

{

cout<<"Invalid lab number"<<endl;

cout<<"Enter the lab number(1-"<<numLabs<<") : ";

cin>>labNumber;

}

// input the computer number

cout<<"Enter the PC number(1-"<<computerInLabs[labNumber-1]<<") : ";

cin>>computerNumber;

// validate computer number for the given lab number, if invalid re-prompt until valid

while(computerNumber < 1 || computerNumber > computerInLabs[labNumber-1])

{

cout<<"Invalid computer number"<<endl;

cout<<"Enter the PC number(1-"<<computerInLabs[labNumber-1]<<") : ";

cin>>computerNumber;

}

// validate if labNumber in computerNumber in free or not

if(labs[labNumber-1][computerNumber-1].compare("Free") == 0)

{

// if free allocate it to the student

labs[labNumber-1][computerNumber-1] = name;

cout<<"Computer number : "<<computerNumber<<" in lab : "<<labNumber<<" allocated to "<<name<<endl;

}

else // not free

cout<<"Computer number : "<<computerNumber<<" in lab : "<<labNumber<<" not free"<<endl;

break;

 

case 3: // log out a student from a computer in the lab

// input the lab number

cout<<"Enter the lab number(1-"<<numLabs<<") : ";

cin>>labNumber;

// validate the labNumber, if invalid re-prompt until valid

while(labNumber < 1 || labNumber > numLabs)

{

cout<<"Invalid lab number"<<endl;

cout<<"Enter the lab number(1-"<<numLabs<<") : ";

cin>>labNumber;

}

// input the computer number

cout<<"Enter the PC number(1-"<<computerInLabs[labNumber-1]<<") : ";

cin>>computerNumber;

// validate computer number for the given lab number, if invalid re-prompt until valid

while(computerNumber < 1 || computerNumber > computerInLabs[labNumber-1])

{

cout<<"Invalid computer number"<<endl;

cout<<"Enter the PC number(1-"<<computerInLabs[labNumber-1]<<") : ";

cin>>computerNumber;

}

// validate if a ny student if allocated in the given computer for the given lab

if(labs[labNumber-1][computerNumber-1].compare("Free") != 0)

{

// if allocated, remove it and set it to free

name = labs[labNumber-1][computerNumber-1];

labs[labNumber-1][computerNumber-1] = "Free";

cout<<name<<" is logged out of computer number : "<<computerNumber<<" in lab number : "<<labNumber<<endl;

}else // computer is free

cout<<"Computer number : "<<computerNumber<<" in lab : "<<labNumber<<" is not allocated"<<endl;

break;

 

case 4: // add new computers to a lab

{

// input the lab number

cout<<"Enter lab number : ";

cin>>labNumber;

// validate the labNumber, if invalid re-prompt until valid

while(labNumber < 1 || labNumber > numLabs)

{

cout<<"Invalid lab number"<<endl;

cout<<"Enter the lab number(1-"<<numLabs<<") : ";

cin>>labNumber;

}

 

int N;

// input the number of computers to add

cout<<"Enter the number of computers to add : ";

cin>>N;

// validate number of computers, if invalid, re-prompt until valid

while(N <= 0)

{

cout<<"Invalid number of computers to add."<<endl;

cout<<"Enter the number of computers to add : ";

cin>>N;

}

// create a new lab with added number of computers

string *newLab = new string[computerInLabs[labNumber-1]+N];

// loop to copy the data from old lab

for(i=0;i<computerInLabs[labNumber-1];i++)

newLab[i] = labs[labNumber-1][i];

computerInLabs[labNumber-1] += N; // add N to array storing the number of computers for labs

// set the new computers to Free state

for(;i<computerInLabs[labNumber-1];i++)

{

newLab[i] = "Free";

}

 

delete labs[labNumber-1]; // delete the old lab

labs[labNumber-1] = newLab; // set old lab to new lab

break;

}

case 5: //exit

break;

}

}while(choice != 5);

 

// delete the memory allocated

for(int i=0;i<numLabs;i++)

delete labs[i];

return 0;

}

 

// function to input and return the user choice

int menu()

{

int choice;

// disply the menu

cout<<"\n1. Print the current status of computers in all labs"<<endl;

cout<<"2. Log in a new student to a computer in the lab"<<endl;

cout<<"3. Log out a student from his/her computer in a lab"<<endl;

cout<<"4. Add more computers in a lab"<<endl;

cout<<"5. Exit"<<endl;

cout<<"Enter a choice(1-5) : ";

// input of choice

cin>>choice;

// validate choice and re-prompt until valid

while(choice < 1 || choice > 5)

{

cout<<"Invalid choice."<<endl;

cout<<"Enter a choice(1-5) : ";

cin>>choice;

}

 

return choice;

}

 

// function to print the details of all computers in all labs

void printLabs(string *labs[], int computerInLabs[], int numLabs)

{

cout<<"Details of labs : "<<endl;

// loop over labs

for(int i=0;i<numLabs;i++)

{

cout<<"Lab-"<<(i+1)<<" : "<<endl;

// loop over each computer in the lab

for(int j=0;j<computerInLabs[i];j++)

{

cout<<left<<setw(5)<<"PC"<<(j+1)<<" : "<<left<<setw(15)<<labs[i][j]<<endl;

}

cout<<endl;

}

}