All Stack Operations

#include<iostream>
#include<string>
using namespace std;

class stack{
	private:
		int top;
		int arr[5];
	public:
		stack(){
			top=-1;
			for(int i=0;i<5;i++){
				arr[i]=0;
			}
		}
		
		bool isEmpty(){
			if(top==-1)
				return true;
			else
				return false;
		}
		
		bool isFull(){
			if (top==4)
				return true;
			else
				return false;
		}
		
		
		void push(int val){
			
			if(isFull()){
				cout<<"stack full";
			}
			else{
				
				top++;
				arr[top] =val;
			}
		}
		
		int pop(){
			
			if(isEmpty()){
				cout<<"stack is empty";
				return 0;
			}
			else{
				int popvalue=arr[top];
				arr[top]=0;
				top--;
				return popvalue;
			}
		}
		
		int coun(){
			return (top+1);
		}
		
		int peek(int pos){
			
			if(isEmpty()){
				cout<<"stack empty<<endl";
				return 0;
			}
			
			else{
				return arr[pos];
			}
		}
		
		void change(int pos,int val){
			
			arr[pos] = val;
			cout<<"value changed at location"<<pos<<endl;
		}
		
		void display(){
			
			cout<<"all the values are"<<endl;
			
			for(int i=4;i>=0;i--){
				cout<<arr[i]<<endl;
			}
		}
		
};

int main(){
	
	
	
	stack s1;
	int option,position,value;
	
	cout<<"MENU"<<endl;
	
	do{
		
		cout<<"select option, enter 0 to exit"<<endl;
		cout<<"1. push"<<endl;
		cout<<"2. pop"<<endl;
		cout<<"3. isEmpty"<<endl;
		cout<<"4. isFull"<<endl;
		cout<<"5. peek"<<endl;
		cout<<"6. count"<<endl;
		cout<<"7. change"<<endl;
		cout<<"8. Display"<<endl;
		cout<<"9. clear screen"<<endl<<endl;
		
		cin>>option;
		switch(option){
			case 0:
				break;
			case 1:
				cout<<"enter value to push"<<endl;
				cin>>value;
				s1.push(value);
				break;
			case 2:
				cout<<"pop function called..."<<s1.pop()<<endl;
				
				break;
			case 3:
				if(s1.isEmpty())
					cout<<"stack is empty"<<endl;
				else
					cout<<"stack is not empty"<<endl;
				break;
			case 4:
				if(s1.isFull())
					cout<<"stack is Full"<<endl;
				else
					cout<<"stack is not Full"<<endl;
				break;
			case 5:
				cout<<"enter position of iteam you want to peak"<<endl;
				cin>>position;
				cout<<"peek function called...value at position"<<position<<"is"<<s1.peek(position)<<endl;
				break;
			case 6:
				cout<<"number of items in stack are"<<s1.coun()<<endl;
				break;
			case 7:
				cout<<"enter position of item you want to change:";
				cin>>position;
				cout<<endl<<"enter value of item you want to change:";
				cin>>value;
				s1.change(position,value);
				break;
			case 8:
				cout<<"display function called"<<endl;
				s1.display();
				break;
			case 9:
				system("cls");
				break;
			default:
				cout<<"enter proper option:"<<endl;
		}
		
	}while(option !=0);
	
	
	return 0;
	
}