How to delete addres pointer in C++

Question

1.00/5 (1 vote)

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i do not understand how to delete addres pointer.

but in my script eror when delete (coba);

example :
Input :
2 3
2 5
2 6
1 2
3
1 2
Output :
Value =5;
(5 deletting)
Value =6;

soo (*coba).nilai = 3 , 6..
5 is delete..
but i do not understand how to do it..
helpp

What I have tried:

#include <iostream>
#include <vector>
 
using namespace std;
 
struct test
{
  int next;
  int previous;
  int value = 0;
};

int main()
{
	test *coba, testt;
	coba = &testt;
	int z;
	int l = 0;
	int perintah;
	int y = 0;
	while(true)
	{
		cout << "Input : ";
		cin >> l;
		if(l == 2)
		{
			cin >> (*coba).value;
			*(++coba);
			y++;
		}
		if(l == 1)
		{
			cin >> z;
			for(int i = 0; i < y-z+1; i++)
			{
				(--coba);
			}
			cout << "Value = " << (*coba).value << endl;
			cout << "1.next / 2.previous / 3.erase : ";
			cin >> perintah;
			if(perintah == 1)
			{
				(++coba);
				testt.next = (*coba).value;
				cout << "Next = " << testt.next << endl;
				for(int i = 0; i < y-z; i++)
				{
					(++coba);
				}
			}
			else if(perintah == 2)
			{
				(--coba);
				testt.previous = (*coba).value;
				cout << testt.previous;
				for(int i = 0; i < y-z+2; i++)
				{
					(++coba);
				}
			}
			else if(perintah == 3)
			{
				delete (&coba);
			}
		}
	}
  return 0;
}

Posted 11-Jul-18 19:37pm

Member 13906640

Updated 11-Jul-18 19:54pm

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Comments

KarstenK 12-Jul-18 2:49am

Normally C++ written this style: coba->value.

Use delete ONLY for pointers which values are to memory (or objects/structs) which are allocted with new. (It is a fundamental rule!!!)

CPallini 12-Jul-18 3:42am

What are you trying to do? Are you implmenting a linked list? Why don't you consider using std::list instead?

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OriginalGriff · Answer 1 · 2018-07-11T19:55:00

As I told you yesterday: Error C++ struct with pointer[^] THOSE AREN'T POINTERS.

C++

struct test
{
  int next;
  int previous;
  int value = 0;
};

next and previous cannot be declared as int - they need top be pointer values and preferably pointers to the actual destination type:

C++

struct test
{
  struct test *next;
  struct test *previous;
  int value = 0;
};

If you don't, then you will get problems. Integers are 32 bit values (in a modern compiler), but on a 64 bit system pointers are 64 bit values: so when you set a pointer to an address you need a destination that has enough space to store an entire 64 bit value, if you don;t have that, then something is going to get overwritten...

To add to that, your "next" code is total garbage!

C++

test *coba, testt;
	coba = &testt;
...
	(++coba);
	testt.next = (*coba).value;

No, you cant just do that - you are using memory you haven't allocated whine you use ++, so you will again start corrupting memory. NAd that last line? What the heck do you expect that to do?

Stop guessing. Read your course notes, and start thinking. Hope and pray is not a viable design strategy...