How to clear dynamically allocated memory using delete [] operator? (Unable to clear with regular delete syntax)

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I have allocated a dynamic memory using int *p = new int[size]; Now when I try to delete it using delete [] p; I'm getting a segmentation fault(core dump) while executing the code.

Initially I was able to enter array elements dynamically and and it was working normally. But, after executing certain number of times, now it says segmentation fault. I have a function where I have allocated memory using new later at the end of the scope of that function I have included delete [] p. Am I supposed to include delete in main function?

#include<iostream>
using namespace std;

void input(){
    int n,d, i= 0, count;
    cout<< "number of variables: "<<" ";
    cin>>n;
    cout<<"enter number of minterms: "<<" ";
    cin>>count;
    int x =  pow(2, n);

    int *p = new int[count] ; //dynamic allocation

    for(i = 0; i<count; i++)
    {   
        cout<< "enter the minterms in decimal: ";
        cin>>d;    
        p[i] = d;
    }

    for( i =0; i< count; i++){
        cout<<p[i]<<" ";
    }

    delete [] p; //(Do I need  to write delete over here or in the main                           
    //func, Right now I've used it here(i.e,the user defined function.)
    cout<<"successfully deallocated";
}

//Main function:
int main(){

    int *p = NULL; //Is this required ?


    input();
    //delete[] p; (Do I need to mention delete over here?)
    return 0;
}

number of variables:  4
enter number of minterms:  8
enter the minterms in decimal: 1
enter the minterms in decimal: 2
enter the minterms in decimal: 3
enter the minterms in decimal: 4
enter the minterms in decimal: 5
enter the minterms in decimal: 6
enter the minterms in decimal: 7
enter the minterms in decimal: 8
1 2 3 4 5 6 7 8 successfully deallocated00000000119614428832765154679997521907-10100852163265911961440643276540008000800080004000-1005...<a lot of numbers>...07370419492536907748609097595Segmentation fault (core dumped)

I have tested your code and for me it runs with no problem.

If you allocate space in main(), then you should also typically deallocate it in main() as well.

Dynamic memory - C++ Tutorials, Dynamic memory is allocated using operator new . new is followed by a data type specifier and, if a This is the purpose of operator delete , whose syntax is:� C uses malloc() and calloc() function to allocate memory dynamically at run time and uses free() function to free dynamically allocated memory. C++ supports these functions and also has two operators new and delete that perform the task of allocating and freeing the memory in a better and easier way.

The pointer p you create in input is independent of the pointer you make in the main. So you can not access the array you make in input when you are back in main.

If that is what you want to do, you "can" not delete p in the input, return it to main, use it in main, and then delete it in main. However splitting new and delete like that is not best coding practices.

If you don't want to use the array in main, you should remove any reference to p in the main function, no need to set it to null, and certainly not delete it.

Memory Management, C++ FAQ, What if I forget the [] when delete ing an array allocated via new T[n] ? Can I Using a resource handle, here the standard library unique_ptr , makes it clear where the But you cannot allocate an object with malloc() and free it using delete . The statement operator delete(p) calls the memory deallocation primitive, void� When the memory is allocated dynamically using new operator, then delete operator is used in C++ to deallocate that memory. malloc() function is used in C for dynamically allocating memory.

Dynamic Memory Allocation, To dynamically allocate memory in C++, we use the new operator. De-allocation: Deallocation is the "clean-up" of space being used for variables or other data int * list = new int[40]; // dynamic array delete [] list; // deallocates the array list = 0; To consider: So what happens if you fail to deallocate dynamic memory when� (Unable to clear with regular delete syntax) I have allocated a dynamic memory using If you don't want to use the array in main, you should remove any

Dynamic Memory Allocation and Classes, Clean up memory with operator delete. Apply to the pointer. Use delete [] form for arrays: When using dynamic allocation of objects, we use pointers, both to single This could happen in regular member functions, wherever space is cleared a dynamically allocated array (perhaps to add space), you cannot just append� You can allocate memory at run time within the heap for the variable of a given type using a special operator in C++ which returns the address of the space allocated. This operator is called new operator. If you are not in need of dynamically allocated memory anymore, you can use delete operator, which de-allocates memory that was previously

operator delete, operator delete[], void operator delete ( void* ptr, std::size_t sz ) noexcept;. (5), (since non- allocating placement deallocation functions and by new-expressions to deallocate memory after destructing (or failing to construct) objects with dynamic storage duration. They may also be called using regular function call syntax. Dynamically allocated memory has dynamic duration and will stay allocated until you deallocate it or the program terminates. Be careful not to dereference dangling or null pointers. In the next lesson, we’ll take a look at using new and delete to allocate and delete arrays.

Top 10 Most Common C++ Mistakes That Developers Make, Learning the language syntax and having good programming skills in similar languages Common Mistake #1: Using “new” and ”delete” Pairs Incorrectly. No matter how much we try, it is very difficult to free all dynamically allocated memory . The delete[] operator will not just delete the memory allocated for an array, but it� Delete is an operator that is used to destroy array and non-array(pointer) objects which are created by new expression. Delete can be used by either using Delete operator or Delete [ ] operator; New operator is used for dynamic memory allocation which puts variables on heap memory. Which means Delete operator deallocates memory from heap.

Comments
  • 1. Avoid huge output text in the questions if you can. 2. You are using C++ as C. Use smart pointers, use nullptr instead of NULL
  • There is nothing in your code that could produce that output.