Structs and linked lists

[oscarocampo]

Can someone please help me understand why pPre->head = NULL is giving me an error. Also why is pLoc = list->head not allowed?

struct node{
	int data;
	node *backward;
	node *forward;
};

struct list{
	int count;
	node *head;
	node *rear;
};

  bool SearchList(int target)
{
	bool found;
	list *pPre = new list;
	list *pLoc = new list;
	
	pPre->head = NULL;
	pLoc = list->head;
}      

[SECMoG1T]

why pPre->head = NULL is giving me an error
what error did you get?

why is pLoc = list->head not allowed?
because list is a type not an object , you would need to use an object of type list
to accomplish what you want.

[oscarocampo]

It says identifier NULL is undefined.

[JLBorges]

> It says identifier NULL is undefined.

#include <cstddef>. Or better: pPre->head = nullptr ;

[MiiNiPaa]

http://en.cppreference.com/w/cpp/types/NULL
Did you include any of the required headers?

[oscarocampo]

I just included all those headers and it still gives me the same error. And it says cannot open source file for all the headers I included

[MiiNiPaa]

I just included all those headers

You just need to include one.

And it says cannot open source file for all the headers I included

It seems that you compiler broke. What do you use?

[oscarocampo]

I am using GNU GCC.

[MiiNiPaa]

Are you sure that it is installed properly? Can you build a simple helloworld example?

#include <iostream>
int main() { std::cout << "Hello, world!\n"; }

[oscarocampo]

I just ran this code and it compiled and ran.

#include <iostream>

using namespace std;

int main()
{
   	cout << "hello world" << endl;

    system("pause");
    return 0;
} // end main()