C++ Tutorial Index

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C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++ Returning Multiple Values from a Function using Tuple and Pair in C++ wcscpy(), wcslen(), wcscmp() Functions in C++ Auto keyword in C++ C++ 11 vs C++ 14 vs C++ 17 C++ STL (Standard Template Library) Differences Between C Structures and C++ Structures Divide by Zero Exception in C++ Dynamic Constructor in C++ Dynamic Memory Allocation in C++ Find the Size of Array in C/C++ without using sizeof() function Floating Point Operations and Associativity in C, C++ and Java Hello World Program in C++ How to create a table in C++ How to Setup Environment for C++ Programming on Mac Implementation of a Falling Matrix in C++ Message Passing in C++ Pointer to Object in C++ Templates in C++ vs Generics in Java Ways to Copy a Vector in C++ What does Buffer Flush mean in C++ sort() function in C++ Structure Sorting (By Multiple Rules) in C++ Similarities between C++ and Java std::distance in C++

Stack in C++

Stack:

The stack is a very popular data structure. It is the form of data structure that follows a particular order called FIFO(First-In-First-Out). In simple words, a stack is an Abstract Data Type used to store a collection of objects.

Various operations are uniquely associated with stacks. They are namely push, pop, and peek.

Let's look out what is a push, pop and peek or top, and isEmpty.

Push: When an element is pushed inside a stack, it is called Push

      operation.

Pop: When an element is removed from the top of the stack, it is

     called as Pop operation.

Peek or Top: This return top element of the stack.

isEmpty: It return true if stack is empty, else return false.

Pre-Requisites:

Before understanding stacks, one must be familiar with the below fundamentals.

  1. Conditional statements like if, else.
  2. Pointers.
  3. Loops like for, while and do while.
  4. Arrays and string primarily.
  5. One object oriented programming language like C++ or Java.

All the above operations have 0(1) complexity and no loop is used.

Let us look at basic syntax of stack operations that we involve while implementing it.

Push:

 void push(int information) {
    if(isNotFull()) {
       top = top + 1;  
       stack[top] = information;
    } else {
       printf("Stack is full.");
    }
 } 

Pop:

 int pop(int data) {
    if(isNotempty()) {
       information = stack[top];
       top = top - 1;  
       return information;
    } else {
       printf("Stack is empty.\n");
    }
 } 

Peek or Top:

 int peekOrTop()
 {
    return stack[top];
 } 

isEmpty:

 bool isEmpty()
 {
    if(top == -1)     //-1 denotes empty
       return true;
    else
       return false;
 } 

The above pseudo codes can be combined to show operations in the following code below.

 #include <bits/stdc++.h>
 using namespace std;
 #define max 1000
 class Stack {
     int top;
 public:
     int a[max];
     Stack() { top = -1; }
     bool push(int y);
     int pop();
     int peek();
     bool isEmpty();
 };
 bool Stack::push(int y)
 {
     if (top >= (max - 1)) {
         cout << "Stack Overflow";
         return false;
     }
     else {
         a[++top] = y;
         cout << y << " is pushed inside stack \n";
         return true;
     }
 }
 int Stack::pop()
 {
     if (top < 0) {
         cout << "Stack Underflow";
         return 0;
     }
     else {
         int x = a[top--];
         return x;
     }
 }
 int Stack::peek()
 {
     if (top < 0) {
         cout << "Stack is Empty";
         return 0;
     }
     else {
         int x = a[top];
         return x;
     }
 }
 bool Stack::isEmpty()
 {
     return (top < 0);
 }
 int main()
 {
     class Stack s;
     s.push(100);
     s.push(200);
     s.push(300);
     cout << s.pop() << "Popped out from stack\n";
     return 0;
 } 

Output:

Stack in C++

Explanation:

In the above code, we have used an object-oriented programming method so that we can handle code complexity and make it more readable.

Let us take into consideration the below algorithms to understand the logic behind our code.

START

  1. Top = 0
  2. Exit

PUSH(STACK,TOP,MAX,ITEM)

  1. Top = max then

    B. Print “Stack full”;

    C. Exit out of the stack.

    Otherwise

  • Top: = Top + 1;        //increasing top
  • Check Stack(Top)= ITEM;
  • End IF
  • Exit

POP_STACK(STACK,TOP,ITEM)

A. IF Top = zero

        Print “Empty Stack”;

        Exit;

  • Otherwise

        ITEM: =Stack (Top);

        Top:=Top – 1;

  •  End IF
  •  Exit

END

These algorithms are usually followed in the above code to show how the push and pop operations are commonly carried out.

Applications of Stacks

The applications of stacks are listed below:

  1. Memory management:

The continuous memory blocks help in memory assignment when it takes place. With stack, we do it functionally and the size of the memory to be allocated will be already known by the compiler. When a functional call is executed, memory is allocated and de-allocated when it is already used. These executions happen at defined intervals so that the users do not have to worry about memory management.

  • Evaluating Expressions and Conversions:

Expressions in stacks primarily work on the operator precedence. Say (2*2)+4 will give us 8 since the * or the parenthesis has higher priority. So, they can also be used for parenthesis matching in an expression when a user has not defined the correct order.

  • Backtracking Occurrences:

For complex algorithms like the 8 -Queens problem of Knights Tour problem, backtracking is specifically used to get to the last point where we found the value. Thus, a stack is very efficient in providing backtracking methods. It was used to get back from the current state we may need the previous state and then got into some other paths.

Insights:

In real-world applications, Stack plays a crucial role in particular. From the application perspective stacks are most applicable in the scientific calculations. The undo option in text editors use the stack to roll back to the previous elements.

In programming, it may be used to reverse a word, language processing, defining, and keeping records in a database, and also used to support recursion.



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