4. Write a C++ program to create a class called STACK using an array of integers. Implement the following operations by overloading the operators + and – i) s1=s1+element; where s1 is an object of the class STACK and element is an integer to be pushed on the top of the stack. ii) s1=s1-; where s1 is an object of the class STACK - operator pops the element. Handle the STACK empty and STACK full conditions. Also display the contents of the stack after each operation, by overloading the operator <<

#include<iostream.h> 

#include<stdlib.h> 

#include<conio.h> 

const int SIZE=5; //Stack size 

//class declaration 

class stack 

{ 

 private: int items[SIZE]; 

             int top; 

             int full(); 

             int empty(); 

 public:  stack() 

{ 

 top=-1; 

 } 

 stack operator--(int); 

 friend stack operator+(stack s1,int elem); 

 friend ostream &operator<<(ostream &os,stack &s1); 

}; 

// checking for Stack overflow 

int stack::full() 

{ 

 if(top==SIZE-1) 

 return 1; 

 else 

 return 0; 

} 

//Checking for stack under flow. 

int stack::empty() 

{ 

 if(top==-1) 

 return 1; 

 else 

 return 0; 

} 

//function for element deletion from the stack 

stack stack::operator--(int ) 

{ 

 if(empty()) 

 { 

 cout<<"Stack underflow\n"; 

 } 

 else 

 {

 cout<<"\nThe element deleted is :" <<items[top]; 

 stack t; 

 t.top=--top; 

 for(int i=0;i<=top;i++) 

 t.items[i]=items[i]; 

} 

return *this; 

} 

ostream &operator<<(ostream &os,stack &s1) 

{ 

 for(int i=s1.top;i>=0;i--) 

 {

     os<<s1.items[i]<<"\n"; 

 }

return os; 

} 

}

//function for element insertion on to the stack 

stack operator+(stack s1,int elem) 

{ 

 if (s1.full()) 

 cout<<"\nStack overflow\n"; 

 else 

 s1.items[++(s1.top)]=elem; 

 return s1; 

} 

void main()  

{ 

 stack s1; 

 int choice,elem; 

 clrscr(); 

 for(;;) 

 { 

 cout<<"\n1:PUSH 2:POP 3:DISPLAY 4:EXIT\n" 

 <<"enter your choice:"; 

 cin>>choice; 

 switch(choice) 

 { 

 case 1: 

 cout<<"Enter the element to be inserted:"; 

 cin>>elem; 

 s1=s1+elem; 

 break; 

 case 2: 

 s1=s1--; 

 break; 

 case 3: 

 cout <<"The contents of the stack are :\n" 

 <<s1; 

 break; 

 case 4: exit(0); 

 default: 

 cout <<"Invalid choice\n"; 

 getch(); 

 exit(0); 

 } 

 } 

} 

OUTPUT 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:2 

Stack underflow 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:1 

Enter the element to be inserted:20 

1:PUSH 2:POP 3:DISPLAY 4:EXIT Bangalore Institute of Technology C++ Lab Manual 

Department of Information Science and Engineering 23 

enter your choice:1 

Enter the element to be inserted:45 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:1 

Enter the element to be inserted:51 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:1 

Enter the element to be inserted:62 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:1 

Enter the element to be inserted:77 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:3 

The contents of the stack are : 

77 

62 

51 

45 

20 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:2 

The element deleted is :77 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:2 

The element deleted is :62 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:3 

The contents of the stack are : 

51 

45 

20 

1:PUSH 2:POP 3:DISPLAY 4:EXIT 

enter your choice:4