From b419d9e7323ce0d502b882a2cee9754085867f1b Mon Sep 17 00:00:00 2001
From: AndreaOrlando23 <64850221+AndreaOrlando23@users.noreply.github.com>
Date: Mon, 4 Oct 2021 07:57:50 +0200
Subject: [PATCH 1/5] [FEAT] first version of queue solution in cpp

---
 .../solutions/aorlando/cpp-version/README.md  |  18 ++
 .../solutions/aorlando/cpp-version/queue.cpp  | 225 ++++++++++++++++++
 2 files changed, 243 insertions(+)
 create mode 100644 challenges/easy/queue/solutions/aorlando/cpp-version/README.md
 create mode 100644 challenges/easy/queue/solutions/aorlando/cpp-version/queue.cpp

diff --git a/challenges/easy/queue/solutions/aorlando/cpp-version/README.md b/challenges/easy/queue/solutions/aorlando/cpp-version/README.md
new file mode 100644
index 0000000..d99dc64
--- /dev/null
+++ b/challenges/easy/queue/solutions/aorlando/cpp-version/README.md
@@ -0,0 +1,18 @@
+# Queue - How does it work?
+
+Queues follow the First-in-First-Out ([FIFO](https://it.wikipedia.org/wiki/FIFO)) principle.
+
+***e.g.*** As if waiting in a queue for the movie tickets, the first one to stand in line is the first one to buy a ticket and enjoy the movie.
+
+I have created a data structure in cpp for a queue able to do the following methods:
+
+  - `enqueue(item)` - adds an item to the queue
+  - `dequeue()` - removes an item from the queue (FIFO)
+  - `peek()` - returns the next item in the queue without removing it
+  - `isEmpty()` - tests to see whether the queue is empty
+  - `size()` - returns the number of items in the queue
+  - `isFull()` - tests to see whether the queue is full
+  - `display()` - return the item inside the queue
+
+  
+  I've also tryed to develop a fancy CLI interface to insert the intructions directly from the user :)
diff --git a/challenges/easy/queue/solutions/aorlando/cpp-version/queue.cpp b/challenges/easy/queue/solutions/aorlando/cpp-version/queue.cpp
new file mode 100644
index 0000000..7e97070
--- /dev/null
+++ b/challenges/easy/queue/solutions/aorlando/cpp-version/queue.cpp
@@ -0,0 +1,225 @@
+#include <iostream>
+using namespace std;
+
+class Queue {
+    private:
+    int front;
+    int rear;
+    int arr[5];
+    int itemCount;
+
+    public:
+    // constructor
+    Queue() {
+        int itemCount = 0;
+        front = -1;
+        rear = -1;
+        for(int i=0; i<5; i++) {
+            arr[i]=0;
+        }
+    }
+
+    void enqueue(int item) {
+        if(isFull()) {
+            cout << "Queue is FULL" << endl;
+            return;
+        }
+        else if(isEmpty()) {
+            rear=0;
+            front=0;
+            arr[rear]=item;
+        }
+        else {
+            /* e.g. 
+            Assume we have added an element in our array that have at least one element already:
+            rear == 0
+            rear + 1 == 1
+            1 % 5 == 1, so rear become == 1
+            then put the new element in the position 1 of our array
+
+            enqueue() again:
+            rear == 1
+            rear + 1 == 2
+            2 % 5 == 2, so rear become == 2
+            then put the new element in the position 2 of our array
+
+            Let's say that we have 5 elements [5 4 3 2 1] in our array so the queue is full.
+            In according to the algorithm, rear is == to 4
+            If we dequeue(), the first element removed is 5
+            then enqueue() the element 6:
+            rear == 4
+            rear + 1 == 5
+            5 % 5 == 0, so rear become == 0
+            then put the new element in the position 0 of our array
+            (see dequeue() method to understand the logic for that process) 
+        */
+            rear = (rear+1)%5;
+            arr[rear]=item;
+            
+        }
+        itemCount++;
+    }
+
+    int dequeue() {
+        int x = 0;
+        if(isEmpty()) {
+            cout << "Queue is EMPTY" << endl;
+            return -1;  //we have to reurn some value couse of the int function
+        }
+        else if(front == rear) {
+            /* 
+            the only chance that could happen is when the arrey has only one element
+            so front and rear come back to the initial situation --> front = rear = -1 
+            */
+            x = arr[front];  // I put the value wich I have to return at the variable x
+            arr[front] = 0;  // I replace the value with a 0
+            front = -1;
+            rear = -1;
+            itemCount--;
+            return x;
+        }
+        else {
+            /* e.g. 
+            Assume we have at least two elements in the array [5 4]:
+            front == 0
+            x = arr[0] --> 5
+            raplace arr[front] with 0 as a placeholder
+
+            (front+1)%5 == 1
+            then front become == 1 
+            in that case, front = rear = 1. So if we dequeue() again, the second condition run
+
+            dequeue() an array with 3 elements [5 4 3]:
+            front == 0
+            x = arr[0] --> 5
+            raplace arr[front] with 0 as a placeholder
+
+            (front+1)%5 == 1
+            then front become == 1 
+            in that case, front = 1 and rear = 2. So if we dequeue() again, the third condition run again
+            
+        */
+            x = arr[front];
+            arr[front] = 0;
+            front = (front+1)%5;
+            itemCount--;
+            return x;
+        }
+    }
+
+    int peek() {
+        if(!isEmpty()) {
+            return arr[front];
+        }
+    }
+
+    bool isEmpty() {
+        if(front==-1 && rear==-1)
+            return true;
+        else
+            return false;
+    }
+
+    int size() {
+        return itemCount;
+    }
+
+    bool isFull() {
+        /* e.g. 
+            Assume we have our array full of elements [5 4 3 2 1]:
+            front == 0
+            rear == 4
+            rear + 1 == 5
+            5 % 5 == 0
+            so (rear+1)%5 == front and then the queue is full and the condition is true
+
+            if we dequeue() one element:
+            front == 1  // (see the dequeue() logic)
+            rear == 4  // it remains the same as before till we enqueue() a new element
+            rear + 1 == 5
+            5 % 5 == 0
+            so (rear+1)%5 != front and then the queue is not full and the condition is false
+        */
+        if((rear+1)%5 == front)
+            return true;
+        else
+            return false;
+    }
+
+    void display() {
+        for(int i=0; i<5; i++) {
+            cout << arr[i] << " ";
+        }
+    }
+
+};
+
+
+int main() {
+
+    Queue test1;
+    int option, item;
+
+    do {
+        cout << "\n\nWhat operation do you want to perform? Select Option number (0 to exit)." << endl;
+        cout << "1. enqueue(item)" << endl;
+        cout << "2. dequeue()" << endl;
+        cout << "3. peek()" << endl;
+        cout << "4. isEmpty()" << endl;
+        cout << "5. size()" << endl;
+        cout << "6. isFull()" << endl;
+        cout << "7. display()" << endl;
+        
+
+        cin >> option;
+
+        switch(option) {
+            case 0:
+                break;
+
+            case 1:
+                cout << "*** Enqueue Operation 1*** \nPlease enter an item to Enqueue in the Queue:"<<endl;
+                cin >> item;
+                test1.enqueue(item);
+                break;
+
+            case 2:
+                cout << "*** Dequeue Operation *** \nDequeued Value: " << test1.dequeue() <<endl;
+                break;
+            
+            case 3:
+                cout << "*** Peek Operation *** \nThe first item is: " << test1.peek() <<endl;
+                break;
+            
+            case 4:
+                if(test1.isEmpty())
+                    cout << "Queue is Empty." << endl;
+                else
+                    cout << "Queue is NOT Empty." << endl;
+                break;
+            
+            case 5:
+                cout << "*** Size Operation *** \nCount of items in Queue: " << test1.size() <<endl;
+                break;
+            
+            case 6:
+                if(test1.isFull())
+                    cout << "Queue is Full." << endl;
+                else
+                    cout << "Queue is NOT Full." << endl;
+                break;
+            
+            case 7:
+                cout << "*** Display Function Called *** \nAll values in the Queue are: ";
+                test1.display();
+                break;
+            
+            default:
+                cout << "Please enter a valid option number. " << endl;
+                break;
+        }
+    }
+    while(option!=0);
+
+    return 0;
+}
\ No newline at end of file

From a92bab2d256e866d5bb8db5a15a816387d4dbd3f Mon Sep 17 00:00:00 2001
From: AndreaOrlando23 <64850221+AndreaOrlando23@users.noreply.github.com>
Date: Mon, 4 Oct 2021 08:06:26 +0200
Subject: [PATCH 2/5] [FEAT] first solution of stack problem in cpp

---
 .../solutions/aorlando/cpp-version/README.md  |  15 ++
 .../solutions/aorlando/cpp-version/stack.cpp  | 148 ++++++++++++++++++
 2 files changed, 163 insertions(+)
 create mode 100644 challenges/easy/stack/solutions/aorlando/cpp-version/README.md
 create mode 100644 challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp

diff --git a/challenges/easy/stack/solutions/aorlando/cpp-version/README.md b/challenges/easy/stack/solutions/aorlando/cpp-version/README.md
new file mode 100644
index 0000000..18654c4
--- /dev/null
+++ b/challenges/easy/stack/solutions/aorlando/cpp-version/README.md
@@ -0,0 +1,15 @@
+# Stack - How does it work?
+
+Stacks follow the Last-in-First-Out ([LIFO](https://it.wikipedia.org/wiki/LIFO)) principle.
+
+***e.g.*** As if stacking coins one one top of the other, the last coin we put on the top is the one that is the first to be removed from stack later.
+
+I have created a data structure in cpp for a stack able to do the following methods:
+
+- `push(item)` - Add an item to the top of the stack.
+- `pop()` - Remove the top item from the stack.
+- `peek()` - Returns a copy of the top item in the stack.
+- `isEmpty()` - Return a boolean indicating whether or not the stack is empty.
+- `size()` - Return the number of items in the stack.
+
+I've also tryed to develop a fancy CLI interface to insert the intructions directly from the user :)
diff --git a/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
new file mode 100644
index 0000000..31bfd46
--- /dev/null
+++ b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
@@ -0,0 +1,148 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+
+class Stack {
+    private:
+    int top;
+    int arr[5];
+
+    public:
+    // constructor
+    Stack() {
+        top = -1;
+        for(int i=0; i<5; i++) {
+            arr[i] = 0;
+        }
+    }
+
+    void push(int item) {
+        if(isFull()) {
+            cout<<"Stack is FULL."<<endl;
+        }
+        else {
+            top++;
+            arr[top] = item;
+        }
+    }
+
+     int pop() {
+        if(isEmpty()) {
+            cout<<"Stack is EMPTY."<<endl;
+            return 0;  // I must return some value couse of the int function
+        }
+        else {
+            int popItem = arr[top];
+            arr[top] = 0;  // Replace the top value with a 0 placeholder
+            top--;
+            return popItem;
+        }
+    }
+
+    int peek() {
+        if(isEmpty()) {
+            cout<<"Stack is EMPTY."<<endl;
+            return 0;
+        }
+        else {
+            return arr[top];
+        }
+    }
+
+    bool isEmpty() {
+        if(top==-1) 
+            return true;
+        else
+            return false;
+    }
+
+    bool isFull() {
+        if (top==4)
+            return true;
+        else
+            return false;
+    }
+
+    int size() {
+        return (top+1);
+    }
+
+    void display() {
+        cout<<"All items in the Stack are: "<<endl;
+        for(int i=4; i>=0; i--) {  // in order to display it in the stack manner
+            cout<<arr[i]<<endl;
+        }
+    }
+};
+
+
+int main() {
+
+    Stack test1;
+    int option, item;
+
+    do {
+        cout << "\n\nWhat operation do you want to perform? Select Option number (0 to exit)." << endl;
+        cout << "1. push(item)" << endl;
+        cout << "2. pop()" << endl;
+        cout << "3. peek()" << endl;
+        cout << "4. isEmpty()" << endl;
+        cout << "5. isFull()" << endl;
+        cout << "6. size()" << endl;
+        cout << "7. display()" << endl;
+        
+
+        cin >> option;
+
+        switch(option) {
+            case 0:
+                break;
+
+            case 1:
+                cout << "*** Push Operation 1*** \nPlease enter an item you want to Stack:"<<endl;
+                cin >> item;
+                test1.push(item);
+                break;
+
+            case 2:
+                cout << "*** Pop Operation *** \nPop Value: " << test1.pop() <<endl;
+                break;
+            
+            case 3:
+                cout << "*** Peek Operation *** \nThe last item inserted is: " << test1.peek() <<endl;
+                break;
+            
+            case 4:
+                if(test1.isEmpty())
+                    cout << "Stack is Empty." << endl;
+                else
+                    cout << "Stack is NOT Empty." << endl;
+                break;
+
+            case 5:
+                if(test1.isFull())
+                    cout << "Stack is Full." << endl;
+                else
+                    cout << "Stack is NOT Full." << endl;
+                break;
+            
+            case 6:
+                cout << "*** Size Operation *** \nCount of items in Stack is: " << test1.size() <<endl;
+                break;
+            
+            case 7:
+                cout << "*** Display Function Called *** \nAll values in the Stack are: ";
+                test1.display();
+                break;
+            
+            default:
+                cout << "Please enter a valid option number. " << endl;
+                break;
+        }
+    }
+    while(option!=0);
+
+    return 0;
+}

From 6ef9a179955596b8468a7febd086e125fdde25ac Mon Sep 17 00:00:00 2001
From: AndreaOrlando23 <64850221+AndreaOrlando23@users.noreply.github.com>
Date: Sat, 9 Oct 2021 10:46:55 +0200
Subject: [PATCH 3/5] refactor: from PR #52 - implement stack challenge using
 vector data structure

---
 .../solutions/aorlando/cpp-version/stack.cpp  | 94 +++++++------------
 1 file changed, 32 insertions(+), 62 deletions(-)

diff --git a/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
index 31bfd46..c830651 100644
--- a/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
+++ b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
@@ -1,85 +1,63 @@
 #include <iostream>
-#include <string>
-
+#include <vector>
 using namespace std;
 
 
-class Stack {
+class Stack 
+{
     private:
-    int top;
-    int arr[5];
+    vector<int> myStack;
 
     public:
-    // constructor
-    Stack() {
-        top = -1;
-        for(int i=0; i<5; i++) {
-            arr[i] = 0;
-        }
-    }
 
     void push(int item) {
-        if(isFull()) {
-            cout<<"Stack is FULL."<<endl;
-        }
-        else {
-            top++;
-            arr[top] = item;
-        }
+        myStack.push_back(item);
     }
 
-     int pop() {
+    int pop() {
+        int x = 0;
         if(isEmpty()) {
-            cout<<"Stack is EMPTY."<<endl;
-            return 0;  // I must return some value couse of the int function
+            cout << "Stack is Empty." << endl;
+            return -1;  //we have to reurn some value couse of the int function
         }
         else {
-            int popItem = arr[top];
-            arr[top] = 0;  // Replace the top value with a 0 placeholder
-            top--;
-            return popItem;
+            x = myStack.size();
+            myStack.pop_back();
+            return myStack[x-1];
         }
     }
 
     int peek() {
-        if(isEmpty()) {
-            cout<<"Stack is EMPTY."<<endl;
-            return 0;
-        }
-        else {
-            return arr[top];
-        }
+        if(!isEmpty()) 
+            return myStack.at(myStack.size() - 1);
+        else 
+            cout << "Stack is Empty." << endl;
+            return -1;
     }
 
     bool isEmpty() {
-        if(top==-1) 
-            return true;
-        else
-            return false;
-    }
-
-    bool isFull() {
-        if (top==4)
+        if(myStack.size() == 0)
             return true;
         else
             return false;
     }
 
     int size() {
-        return (top+1);
+        return myStack.size();
     }
 
     void display() {
-        cout<<"All items in the Stack are: "<<endl;
-        for(int i=4; i>=0; i--) {  // in order to display it in the stack manner
-            cout<<arr[i]<<endl;
+        if (isEmpty())
+            cout << "|None";
+        cout << "|";
+        for(int i = 0; i < myStack.size(); i++) {
+            cout << myStack[i] << "|";
         }
     }
 };
 
 
 int main() {
-
     Stack test1;
     int option, item;
 
@@ -89,9 +67,8 @@ int main() {
         cout << "2. pop()" << endl;
         cout << "3. peek()" << endl;
         cout << "4. isEmpty()" << endl;
-        cout << "5. isFull()" << endl;
-        cout << "6. size()" << endl;
-        cout << "7. display()" << endl;
+        cout << "5. size()" << endl;
+        cout << "6. display()" << endl;
         
 
         cin >> option;
@@ -101,7 +78,7 @@ int main() {
                 break;
 
             case 1:
-                cout << "*** Push Operation 1*** \nPlease enter an item you want to Stack:"<<endl;
+                cout << "*** Push Operation 1*** \nPlease enter an item to push in the Stack:"<<endl;
                 cin >> item;
                 test1.push(item);
                 break;
@@ -111,7 +88,7 @@ int main() {
                 break;
             
             case 3:
-                cout << "*** Peek Operation *** \nThe last item inserted is: " << test1.peek() <<endl;
+                cout << "*** Peek Operation *** \nThe first item inserted in Stack is: " << test1.peek() <<endl;
                 break;
             
             case 4:
@@ -120,20 +97,13 @@ int main() {
                 else
                     cout << "Stack is NOT Empty." << endl;
                 break;
-
+            
             case 5:
-                if(test1.isFull())
-                    cout << "Stack is Full." << endl;
-                else
-                    cout << "Stack is NOT Full." << endl;
+                cout << "*** Size Operation *** \nCount of items in Stack: " << test1.size() <<endl;
                 break;
             
             case 6:
-                cout << "*** Size Operation *** \nCount of items in Stack is: " << test1.size() <<endl;
-                break;
-            
-            case 7:
-                cout << "*** Display Function Called *** \nAll values in the Stack are: ";
+                cout << "*** Display Function Called *** \nAll items in the Stack are: ";
                 test1.display();
                 break;
             
@@ -145,4 +115,4 @@ int main() {
     while(option!=0);
 
     return 0;
-}
+}
\ No newline at end of file

From 84484fec869c4d2ee98c8048ab3f6fd104e2b9dc Mon Sep 17 00:00:00 2001
From: AndreaOrlando23 <64850221+AndreaOrlando23@users.noreply.github.com>
Date: Sun, 10 Oct 2021 00:19:33 +0200
Subject: [PATCH 4/5] refactor: improve methods logic of Stack class

---
 .../solutions/aorlando/cpp-version/stack.cpp  | 30 +++++++++----------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
index c830651..bf77b48 100644
--- a/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
+++ b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
@@ -17,29 +17,29 @@ class Stack
     int pop() {
         int x = 0;
         if(isEmpty()) {
-            cout << "Stack is Empty." << endl;
-            return -1;  //we have to reurn some value couse of the int function
+            cout << "Stack is Empty. The values in stack are: ";
+            return 0;  //we have to return some value couse of the int function
         }
         else {
             x = myStack.size();
             myStack.pop_back();
+            cout << "Pop value: ";
             return myStack[x-1];
         }
     }
 
     int peek() {
-        if(!isEmpty()) 
+        if(!isEmpty()){
+            cout << "The first item inserted in Stack is: ";
             return myStack.at(myStack.size() - 1);
+        }
         else 
-            cout << "Stack is Empty." << endl;
-            return -1;
+            cout << "Stack is Empty. The values in stack are: ";
+            return 0;
     }
 
     bool isEmpty() {
-        if(myStack.size() == 0)
-            return true;
-        else
-            return false;
+        return myStack.size() == 0;
     }
 
     int size() {
@@ -47,8 +47,6 @@ class Stack
     }
 
     void display() {
-        if (isEmpty())
-            cout << "|None";
         cout << "|";
         for(int i = 0; i < myStack.size(); i++) {
             cout << myStack[i] << "|";
@@ -78,17 +76,17 @@ int main() {
                 break;
 
             case 1:
-                cout << "*** Push Operation 1*** \nPlease enter an item to push in the Stack:"<<endl;
+                cout << "*** Push Operation 1***\nPlease enter an item to push in the Stack:"<<endl;
                 cin >> item;
                 test1.push(item);
                 break;
 
             case 2:
-                cout << "*** Pop Operation *** \nPop Value: " << test1.pop() <<endl;
+                cout << "*** Pop Operation ***\n" << test1.pop() <<endl;
                 break;
             
             case 3:
-                cout << "*** Peek Operation *** \nThe first item inserted in Stack is: " << test1.peek() <<endl;
+                cout << "*** Peek Operation ***\n" << test1.peek() <<endl;
                 break;
             
             case 4:
@@ -99,11 +97,11 @@ int main() {
                 break;
             
             case 5:
-                cout << "*** Size Operation *** \nCount of items in Stack: " << test1.size() <<endl;
+                cout << "*** Size Operation ***\nCount of items in Stack: " << test1.size() <<endl;
                 break;
             
             case 6:
-                cout << "*** Display Function Called *** \nAll items in the Stack are: ";
+                cout << "*** Display Function Called ***\nAll items in the Stack are: ";
                 test1.display();
                 break;
             

From 65b28e8fc9cf3817688579dd3844c1ab929202cf Mon Sep 17 00:00:00 2001
From: Andrea Orlando <andrea.orlando87@gmail.com>
Date: Tue, 12 Oct 2021 10:15:08 +0200
Subject: [PATCH 5/5] refactor: removed every cout << statement from methods of
 Stack class and improve readability of CLI interface

---
 .../solutions/aorlando/cpp-version/stack.cpp  | 56 +++++++++----------
 1 file changed, 27 insertions(+), 29 deletions(-)

diff --git a/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
index bf77b48..b1913b5 100644
--- a/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
+++ b/challenges/easy/stack/solutions/aorlando/cpp-version/stack.cpp
@@ -3,8 +3,8 @@
 using namespace std;
 
 
-class Stack 
-{
+class Stack {
+
     private:
     vector<int> myStack;
 
@@ -15,27 +15,13 @@ class Stack
     }
 
     int pop() {
-        int x = 0;
-        if(isEmpty()) {
-            cout << "Stack is Empty. The values in stack are: ";
-            return 0;  //we have to return some value couse of the int function
-        }
-        else {
-            x = myStack.size();
-            myStack.pop_back();
-            cout << "Pop value: ";
-            return myStack[x-1];
-        }
+        int x = myStack.size();
+        myStack.pop_back();
+        return myStack[x-1];
     }
 
     int peek() {
-        if(!isEmpty()){
-            cout << "The first item inserted in Stack is: ";
-            return myStack.at(myStack.size() - 1);
-        }
-        else 
-            cout << "Stack is Empty. The values in stack are: ";
-            return 0;
+        return myStack.at(myStack.size() - 1);
     }
 
     bool isEmpty() {
@@ -46,11 +32,8 @@ class Stack
         return myStack.size();
     }
 
-    void display() {
-        cout << "|";
-        for(int i = 0; i < myStack.size(); i++) {
-            cout << myStack[i] << "|";
-        }
+    vector<int> display() {
+        return myStack;
     }
 };
 
@@ -58,6 +41,7 @@ class Stack
 int main() {
     Stack test1;
     int option, item;
+    vector<int> stack;
 
     do {
         cout << "\n\nWhat operation do you want to perform? Select Option number (0 to exit)." << endl;
@@ -82,11 +66,17 @@ int main() {
                 break;
 
             case 2:
-                cout << "*** Pop Operation ***\n" << test1.pop() <<endl;
+                if(test1.isEmpty())
+                    cout << "Stack is Empty." << endl;
+                else
+                    cout << "*** Pop Operation ***\nPop item: " << test1.pop() <<endl;
                 break;
             
             case 3:
-                cout << "*** Peek Operation ***\n" << test1.peek() <<endl;
+                if(test1.isEmpty())
+                    cout << "Stack is Empty." << endl;
+                else
+                    cout << "*** Peek Operation ***\nThe last item inserted in Stack is: " << test1.peek() <<endl;
                 break;
             
             case 4:
@@ -101,8 +91,16 @@ int main() {
                 break;
             
             case 6:
-                cout << "*** Display Function Called ***\nAll items in the Stack are: ";
-                test1.display();
+                if(test1.isEmpty())
+                    cout << "Stack is Empty." << endl;
+                else {
+                    cout << "*** Display Function Called ***\nAll items in the Stack are: ";
+                    stack = test1.display();
+                    cout << "|";
+                    for(int i = 0; i < stack.size(); i++) {
+                        cout << stack[i] << "|";
+                    }
+                }
                 break;
             
             default: