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++

Delete Operator in C++

Overview

We can reserve allocation for a variable or an array at runtime in C++. Dynamic memory allocation is the term for this. After utilising a variable in C++, we must manually deallocate the dynamically allocated memory. Using the delete operators, we may dynamically deallocate memory.

Memory Management : An Overview

The new and delete operators in C++ provide dynamic memory (that is, the allocation of memory or at runtime by the programmer) and object allocation and deallocation.

When you no longer need to utilise a dynamically defined variable in C++, you can deallocate the memory used by the variable by using the "delete" operator.

You may use the delete operators to allocate memory to the array at runtime, which is one of the applications or uses of dynamic memory allocation in data structures.

Delete Operator in C++ :

Because the coder has allotted space at runtime, it is the programmer's responsibility to destroy that memory when it is no longer needed. When programmers decide that a dynamically created variable is no longer needed, they can use the "delete" operator to free up the memory it takes in the free store or heap. The memory is returned to the operating system. Memory deallocation is another name for this. Additionally, after the programme is finished, memory will be automatically deallocated.

Syntax :

For deallocating memory for only one element.

delete pointer_var;

For deallocating memory for an array.

delete [] pointer_var;

In the aforementioned syntaxes, memory that was pointed by pointer_var has been removed.

For example :

delete scalar

The memory indicated by the variable 'scalar' will be deallocated in the provided example.

It's beneficial to employ dynamic memory allocation for flexibility and other purposes, however if the programmer fails to deallocate memory, a memory leak might occur (in which memory is not deallocated until the programme terminates). For good coding practise and to minimise memory leaks, programmers should explicitly erase the dynamically allocated memory.

Why is delete operator required ?

We all know that when a programme exits or shuts down, variables are automatically deallocated/deleted, but it's important to use the delete operator in order to reuse the memory allocated in the programme if necessary and avoid situations like memory not being left or allocation of a space having an unknown value.

Using the delete() method to delete an array object :

In C++, the delele [] operator may be used to efficiently delete array objects. We'll show you how to remove arrays in C++ in the code below.

Example :

#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    // Allocating the Heap memory 
    int* arr = new int[7];  
      
    // Deallocating the Heap memory 
    delete[] arr;  
    cout << "Array Deleted." << endl;
    return 0; 
}

Output :

Array Deleted.

Explanation :

In the above example, we created a new array called arr first, using new keyword to allocate the heap memory. Then we used the delete[] method to deallocate the heap memory and erase the data. Thus, we got our required output.

Using the delete() method to delete NULL pointers :

The pointer to the object or variable is not removed during the delete operation on pointers. As a result, the delete operation clears the RAM memory region to which the pointer corresponds.

Example :

#include <bits/stdc++.h> 
using namespace std; 
  	
int main() 
{ 
    // pntr is the given NULL pointer 
    int* pntr = NULL; 
  
    // deleting the pntr 
    delete pntr; 
    
    cout<<"NULL pointer Deleted"<<endl;
    return 0; 
}

Output :

NULL pointer Deleted

Explanation :

In the above example, a NULL pointer was given as a Pointer which was allocated in the memory. Using the delete method we deallocated that NULL pointer from the memory successfully. Thus, the memory held by the NULL pointer variable has been deleted.

Using the delete operator to delete a void pointer :

The delete operator may be used to efficiently clear up memory space taken up by the void pointer variable.

Example :

#include <bits/stdc++.h> 
using namespace std; 
 
int main() 
{ 
    void* strng;   
    
    delete strng;
  
    cout<<"Void Pointer Deleted"<<endl;
    return 0; 
}

Output :

Void Pointer Deleted

Explanation :

In the above example, a void pointer named strng was allocated to the memory. Then we used the delete operator to deallocate the void pointer strng from the memory.

Using the delete() method to erase dynamically allocated memory :

The delete operator can be used to erase memory that has been dynamically allocated to the pointer variable using the malloc() method.

Example :

#include <bits/stdc++.h> 
using namespace std; 
 
int main() 
{ 
    char* strng = (char*)malloc(sizeof(char));
     
    delete strng; 
    
    cout<<"Pointer memory allocated dynamically is Deleted"<<endl;
    return 0; 
}

Output :

Pointer memory allocated dynamically is Deleted

Explanation :

In the above example, the pointer variable strng was allocated memory dynamically. Then the delete operator was used to erase memory that has been dynamically allocated to the pointer variable using the malloc() method.



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