C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

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++ Array program in C++ C++ Tricks for Competitive Programming Desired Capabilities in Selenium Web Driver in C++ Socket Programming in C++ Template Specialization in C++ Classes and Objects in C++ Convex hull Algorithm in C++ DES in C++ C++ vardiac() function Difference between Two Sets in C++ Difference between Exit and Return Structured Binding in C++ Differences between Local and Global Variable Bitwise Operator vs Logical Operator Difference between OOP and POP in C++ Fork in C++ Functors in C++ How to call a void function in C++ How to create a directory or folder in C/C++ How to create a library in C++ How to create a stack in C++ How to create the Processes with Fork in C++ How to Handle Divide by Zero Exception in C++ Lambda Expression in C++ Pattern programs in C++ Roadmap to C++ Programming Substring in C++ Virtual base class in C++ Bits stdc++.h in C++ Top 14 Best Free C++ IDE (Editor & Compiler) for Windows in 2022 Bitmasking in C++ Auto Keyword in C++ Features of OOPS in C++ Hospital Management Project in C++ How to Declare Unordered Sets in C++ How to Sort an Array in C++ Include Guards in C++ Iostream in C++ Method overriding in C++ How to run program in turbo c++ How to Use Getline in C++ Leap Year Program in C++ Naming Convention in C++ New Operator in C++ Nullptr in C++ Object Slicing in C++ Principles of Object-Oriented Programming in C++ Processing strings using std string stream in C++ Pure Virtual 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in C/C++ Depth First Search Program to Traverse a Graph in C++ Features and Use Of Pointers in C/C++ Fread Function in C++ Programming Fscanf Function in The C++ Functions in C++ With Types and Examples Gmtime Function in C/C++ How is Multiset Implemented in C++ How to Build a Program in C++ How to Declare a 2d Array Dynamically in C++ inheritance Program in C++ int Max and int Min in C/C++ is It Fine to Write Void Main Or Main in C/C++ How to create a button in C++ abs() function in C++ Compile Time Polymorphism in C++ Division in C++ Factorial of a Number in C++ using while Loop Multiset in C++ 4 Pillars of OOPs Approach in C++ Backtracking Time Complexity in C++ C++ Global Variable C++ Pipe Tutorial Observer Design Pattern in C++ Private Inheritance in C++ Pthread in C++ Parameters SDL library in C++ with Examples Pointers in C++ Abstract Factory Design Pattern in C++ Ascending order in C++ How the value is passed in C++ Call by Pointer in C++ Constexpr in C++ Deadlock in C++ Design 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New Operator in C++

Dynamic memory allocation in C++ means manually allocating the memory by the developer duing run-time. The dynamic memory is allocated in the heap section of the RAM, whereas the static memory is allocated in the stack section. Therefore, during dynamic allocation, data is stored in the heap data structure in the RAM. This process of dynamic allocation is done using the new operator. This new operator can be used for predefined and custom data types. These kinds of dynamically allocated constructors are used to reduce memory usage.

Syntax

The syntax for a new operator in C++

pointer_variable_of_data_type = new data type;

Examples for using a new operator:

int *ptr = NULL;
 ptr = new int();

Here, the pointer is declared with variable ptr, and we have assigned null to the variable. We can pass the parameters in the int().

We can use the new operator to use in the array, such as:

int* myarray = NULL;
myarray = new int[10];

Example:1

#include <iostream>
using namespace std;


int main() {


  // declare an int pointer
  int* pointInt;


  // declare a float pointer
  float* pointFloat;


  // dynamically allocate memory
  pointInt = new int;
  pointFloat = new float;


  // assigning value to the memory
  *pointInt = 39;
  *pointFloat = 69.45f;


  cout << *pointInt << endl;
  cout << *pointFloat << endl;


  // deallocate the memory
  delete pointInt;
  delete pointFloat;


  return 0;
}

Output:

New Operator in C++

Explanation:

In this code, we have declared two pointers in the main function in the above example. These are pointInt, which stores the integer value, and pointFloat to store the float value in the same function. We have used a new statement for the above two variables and then passed two values for the variables. Then we printed the two variables using the cout statement.

Example:2 Using new statement for arrays:

#include <iostream>
using namespace std;


int main() {


  int num;
  cout << "Enter total number of students: ";
  cin >> num;
  float* ptr;


  // memory allocation of num number of floats
  ptr = new float[num];


  cout << "Enter GPA of students." << endl;
  for (int i = 0; i < num; ++i) {
    cout << "Student" << i + 1 << ": ";
    cin >> *(ptr + i);
  }


  cout << "\nShowing GPA of students." << endl;
  for (int i = 0; i < num; ++i) {
    cout << "Student" << i + 1 << ": " << *(ptr + i) << endl;
  }


  // ptr memory is released
  delete[] ptr;


  return 0;
}

Output:

New Operator in C++

Explanation:

We have created an array using a new statement in the above example. Using for loop, we have entered the values in the array, and then we printed the values in the array using the cout statement. At last, we have used the delete statement, which is used to deallocate memory dynamically.

Example:3

#include <iostream>
using namespace std;


class Student {
  string name;


  public:


    Student() {
      // Constructor
      cout << "Greeting from constructor";
    }
};


int main() {
  // creating student object using the new keyword
  Student * student = new Student();


  return 0;


}

Output:

New Operator in C++

Explanation:

In the above code, we have created a class Student inside which we have declared a constructor with the same name as the class. Inside the class, we have declared a written cout statement. In the main function, we created an object for the class using the new statement.

Example: 4

#include<iostream>
using namespace std;


class example
{
  int num1;
  int num2;
  int *ptr;


public:
  // default constructor (here, it is a dynamic constructor also)
  example()
  {
    num1 = 0;
    num2 = 0;
    ptr = new int;
  }


  //dynamic constructor with parameters
  example(int x, int y, int z)
  {
    num1 = x;
    num2 = y;


    ptr = new int;
    *ptr = z;
  }


 void display()
 {
   cout << num1 << " " << num2 << " " << *ptr;
 }
};


int main()
{
  example obj1;
  example obj2(20, 50, 1);


  obj1.display();
  cout << endl;


  obj2.display();
}

Output:

New Operator in C++

Explanation:

We used the dynamic constructor in the above example and passed a few arguments. Similarly, as in the previous example, we have created a variable with a new statement. Unlike in the previous example, we have passed a few arguments