C++ New::operator delete[]

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The C++ New::operator delete[] is a regular function that can be explicitly called like any other function. By using the delete[] operator, an expression first calls the relevant destructors for each element in the array (if they are of a class type), and then it calls an array deallocation function.

A member function with the name operator delete[] exists, performs the array deallocation for a class object. The global function operator delete[] is used in all other situations. Only global array deallocation functions are taken into consideration when the delete[] statement is preceded by the scope operator.

Syntax

Following is the syntax for C++ New::operator delete[] −

void operator delete[] (void* ptr) throw();    (ordinary delete)
void operator delete[] (void* ptr, const std::nothrow_t& nothrow_constant) throw();     (ordinary delete)
void operator delete[] (void* ptr, void* voidptr2) throw();            (placement delete)

Parameters

  • size − It contain size in bytes of the requested memory block.
  • nothrow_value − It contains the constant nothrow.
  • ptr − It is a pointer to an already-allocated memory block of the proper size.
  • voidptr2 − It is a void pointer.

Example 1

Let's look into the following example, where we are going to use the operator delete[] and retriveing the output.

#include <iostream>
using namespace std;
struct C {
   C() {
      cout << "Welcome" << endl;
   }
   ~C() {
      cout << "TP" << endl;
   }
};
int main() {
   C *p = new C;
   cout << "pass" << endl;
   delete[] p;
   return 0;
}

Output

Let us compile and run the above program, this will produce the following result −

Welcome
pass
TP
TP
TP
TP
TP
........

Example 2

Let's look into the another scenario, where we are going to use the operator delete[].

#include <iostream>
using namespace std;
int main() {
   int *p = new int;
   cout << "Welcome To World" << endl;
   delete[] p;
   return 0;
}

Output

On running the above code, it will display the output as shown below −

Welcome To World

Example 3

Considering the following where we are going to check the functioning of operator delete[].

#include <cstdio>
#include <cstdlib>
#include <new>
void operator delete[](void* ptr) noexcept {
   std::puts("TutorialsPoint");
   std::free(ptr);
}
int main() {
   int* p2 = new int[10];
   delete[] p2;
}

Output

when the code gets executed, it will generate the output as shown below −

TutorialsPoint

Example 4

Let's consider another example, where we are going to use operator delete[] and retrive the output.

#include <iostream>
struct MyClass {
   MyClass() {
      std::cout <<"MyClass is constructed\n";
   }
   ~MyClass() {
      std::cout <<"MyClass is destroyed\n";
   }
};
int main () {
   MyClass * pt;
   pt = new MyClass[3];
   delete[] pt;
   return 0;
}

Output

when the code gets executed, it will generate the output as shown below −

MyClass is constructed
MyClass is constructed
MyClass is constructed
MyClass is destroyed
MyClass is destroyed
MyClass is destroyed
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