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++

Malloc() and new in C++

In C ++, malloc () and new are used for the same thing. During runtime, they are used to allocate memory. Malloc () and the new, on the other hand, have different syntax. The basic difference between malloc () and new is that new is the operator, whereas malloc () is the default standard library function in the stdlib header file.

What do you mean by new?

New is a memory allocation operator used at runtime for memory allocation. The heap stores the memory allocated by the new operator. It returns the initial address of the memory, which is then allocated to the variable. The new operator in C ++ is similar to the malloc () function in C programming language in terms of functionality. Although the malloc () method is also compatible with C ++, newer operators are more commonly used because of its advantages.

type_variable = new type(parameter_list); //syntax

Explanation:

  • Specifies the data type of this variable for which new operators are allocating memory.
  • The name of the variable that points to memory is a variable.
  • The parameter list is a list of initialized values for a variable.

The sizeof () operator is not used to allocate memory by the new operator. It also avoids using the resize operator as the new operator creates enough memory for the object. It is a structure that calls the object () {[original code]} function to initialize the object at the moment of declaration. Because the new operator allocates memory in the heap, an exception is thrown out if the new operator tries to allocate it, but no memory is available in the heap. If our code is unable to handle the exception, the application will terminate unexpectedly.

Example of a program containing new operator in C++:

#include <iostream>
#include <stdlib.h>
#include <bits/stdc++.h>  
using namespace std;  
int main()  
{  
 int *A;  // integer pointer variable declaration  
 A=new int; // allocating memory to the pointer variable A.  
 std::cout << "Еnter the number : " << std::endl;  
 std::cin >>*A;  
 std::cout << "Еntered number is " <<*A<< std::endl;  
 return 0;  
}  

OUTPUT:

enter number : 10
entered number is 10
……….Program finished with exit code 0
Press any key to continue

Explanation:

In the above example a pointer variable of type int is initialized and new operator is allocating memory to the pointer variable A.

What do you mean by malloc() ?

A malloc() function is a runtime memory allocation function. This method returns a void pointer, which may be given to any kind of pointer. This void pointer can be typecast to get a pointer that refers to a certain type of memory.

type variable_name = (type *)malloc(sizeof(type));  //syntax

Explanation:

  • The data type of the variable for which memory must be allocated is called type.
  • Variable name Specifies the name of the memory-pointing variable.
  • 'type*' is used for typecasting, which allows us to get a given type of pointer pointing towards memory.
  • The malloc () method uses the sizeof () operator to determine the amount of memory required for allocation.

Important: To give the pointer a new type, typecasting is required because the malloc () operation returns the void pointer. Because the malloc () method returns raw memory, the sizeof () operator is required in the malloc () function to indicate how much memory is required for allocating the malloc () function.

Example of a program showing how to malloc() function works:

#include <iostream> 
#include <bits/stdc++.h> 
#include<stdlib.h>  
using namespace std;  
int main()  
{  
  int length;   // variable declaration  
  std::cout << "Еnter the count of numbers: " << std::endl;  
  std::cin >> length;  
  int *A; // pointer variable declaration  
  A=(int*) malloc(sizeof(int)*length);  // allocating memory to  the poiner variable  
  for(int i=0;i<length;i++)  
  {  
      std::cout << "Еnter a number: " << std::endl;  
      std::cin >> *(A+i);  
  }  
  std::cout << "Еntered elements are : " << std::endl;  
   for(int i=0;i<length;i++)  
  {  
     std::cout << *(A+i) << std::endl;  
  }  
free(A);  
    return 0;  
}  

OUTPUT:

enter the count of numbers: 5
enter a number: 12
enter a number: 14
enter a number: 18
enter a number: 17
enter a number: 10
entered elements are: 
12
14
18
17
10
……….Program finished with exit code 0
Press any key to continue

If the free() method is not used correctly, it might result in a hanging reference. Such case example is given below:

#include <iostream>  
#include<stdlib.h>  
using namespace std;  
int *function()  
{  
    int *A;  
    A=(int*) malloc(sizeof(int));  
    free(A);  
    return A;  
}  
int main()  
{  
 int *A;  
 A=function();  
 free(A);  
    return 0;  
}

Explanation:

The function () function is called in the above code. Integer is returned by the pointer function () function. We have declared a * A pointer within the function () method and memory is allocated to this pointer variable using the malloc () function. In this example, we are returning a pointer that has already been freed from memory. Because it points to the free memory address, A is the swinging pointer. Alternatively, we can argue that A refers to memory that is not specified by the pointer.



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