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linked list errors

Mar 31st, 2007

I have a program that creates a linked list and is required to count the number of elements in the list. This is what I have thus far.

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include <iostream> 
 
 
using namespace std; 
 
struct listrec 
    { 
       int value; 
       struct listrec *next; 
    }; 
    listrec e1,e2,e3; 
 
int listsize(listrec); 
struct listrec* temp; 
 
int main() 
{ 
    e1.value = 4; 
    e1.next  = &e2; 
    e2.value = 5; 
    e2.next  = &e3; 
    e3.value = 3; 
    e3.next  = NULL; 
 
    int sum = 0; 
    cout << "The list size is " << listsize(*temp); 
 
    system("pause"); 
    return 0; 
 
} 
 
 
int listsize(listrec *p) 
{ 
    struct listrec* temp  = p; 
    int num=0; 
    do{ 
            temp = temp -> next; 
            num++; 
      }while(temp!= NULL); 
    return num; 
 
 
}
#include <iostream> 


using namespace std; 

struct listrec 
    { 
       int value; 
       struct listrec *next; 
    }; 
    listrec e1,e2,e3; 

int listsize(listrec); 
struct listrec* temp; 

int main() 
{ 
    e1.value = 4; 
    e1.next  = &e2; 
    e2.value = 5; 
    e2.next  = &e3; 
    e3.value = 3; 
    e3.next  = NULL; 

    int sum = 0; 
    cout << "The list size is " << listsize(*temp); 

    system("pause"); 
    return 0; 

} 


int listsize(listrec *p) 
{ 
    struct listrec* temp  = p; 
    int num=0; 
    do{ 
            temp = temp -> next; 
            num++; 
      }while(temp!= NULL); 
    return num; 


}

I get the following error on compilation.

[Linker error] undefined reference to `listsize(listrec)'

Please advise.

Last edited by WaltP; Mar 31st, 2007 at 9:39 pm. Reason: Added CODE tags. Please use them!

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Re: linked list errors

Mar 31st, 2007

Can someone help, please?

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Re: linked list errors

Mar 31st, 2007

You forgot the pointer in the function prototype:

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int listsize(listrec*);

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Re: linked list errors

Mar 31st, 2007

Thanx joe. I made the change and a new error. I'm uncertain about the syntax. I need the count of nodes or size of list returned; what should the parameter be in that case?

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include <iostream>
using namespace std;
struct listrec
    {
       int value;
       struct listrec *next;
    };
    listrec e1,e2,e3;
 
int listsize(listrec*);
 
int main()
{   struct listrec* temp;  
 
    e1.value = 4;
    e1.next  = &e2;
    e2.value = 5;
    e2.next  = &e3;
    e3.value = 3;
    e3.next  = NULL;
 
    int sum = listsize(*temp);
 
    cout << "The list size is " << sum;
 
    system("pause");
    return 0;
}
int listsize(listrec *p)
{
    struct listrec* temp = p;
    int num=0;
    do{
            temp = temp -> next;
            num++;
 
      }while(temp!= NULL);
    return num;
)
#include <iostream>
using namespace std;
struct listrec
    {
       int value;
       struct listrec *next;
    };
    listrec e1,e2,e3;
    
int listsize(listrec*);

int main()
{   struct listrec* temp;  
 
    e1.value = 4;
    e1.next  = &e2;
    e2.value = 5;
    e2.next  = &e3;
    e3.value = 3;
    e3.next  = NULL;
         
    int sum = listsize(*temp);
         
    cout << "The list size is " << sum;
    
    system("pause");
    return 0;
}
int listsize(listrec *p)
{
    struct listrec* temp = p;
    int num=0;
    do{
            temp = temp -> next;
            num++;
        
      }while(temp!= NULL);
    return num;
)

25 D:\ cannot convert `listrec' to `listrec*' for argument `1' to `int listsize(listrec*)'

Last edited by WaltP; Mar 31st, 2007 at 9:41 pm. Reason: Added CODE tags again.

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Re: linked list errors

Mar 31st, 2007

>int sum = listsize(*temp);
Try removing the *. And what in the world is "temp" doing in your program? You haven't even assigned it to anything when you pass it as an argument to listsize() !

Last edited by John A; Mar 31st, 2007 at 8:44 pm.

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Re: linked list errors

Mar 31st, 2007

I think I have been going at this all wrong. Let me state the rquirements:
Write a function called listsize that takes a pointer to start of linked list and returns number of elements.
Write a main to create linked list of 4,5,3 as value1,value2,value3 and the call the function to calculate the size and print it.
Here is what I have:

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include <iostream>
using namespace std;
struct listrec
    {
       int value;
       struct listrec *next;
    };
 
 
int listsize(int);
struct listrec *p;
int main()
{     
    struct listrec e1,e2,e3;
    e1.value = 4;
    e1.next  = &e2;
    e2.value = 5;
    e2.next  = &e3;
    e3.value = 3;
    e3.next  = NULL;
   int x =0; 
 
    int sum = listsize(&x);
 
    cout << "The list size is " << sum;
 
    system("pause");
    return 0;
}
int listsize(int &x)
{
 
    int num=0;
 
    while(*p!= NULL);
    {
           *p = *p -> next;
            num++;
 
      }
    return num;
}
#include <iostream>
using namespace std;
struct listrec
    {
       int value;
       struct listrec *next;
    };
    
    
int listsize(int);
struct listrec *p;
int main()
{     
    struct listrec e1,e2,e3;
    e1.value = 4;
    e1.next  = &e2;
    e2.value = 5;
    e2.next  = &e3;
    e3.value = 3;
    e3.next  = NULL;
   int x =0; 
         
    int sum = listsize(&x);
         
    cout << "The list size is " << sum;
    
    system("pause");
    return 0;
}
int listsize(int &x)
{
    
    int num=0;
    
    while(*p!= NULL);
    {
           *p = *p -> next;
            num++;
        
      }
    return num;
}

new error:
26 D: invalid conversion from `int*' to `int'
D: In function `int listsize(int&)':
39 no match for 'operator!=' in '*p != 0'

Last edited by WaltP; Mar 31st, 2007 at 9:41 pm. Reason: Added CODE tags, again

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Re: linked list errors

Mar 31st, 2007

*groan*

Your code was almost there, but now you wrecked it...

>Write a function called listsize that takes a pointer to start of linked list
OK, think about this. Where is the start of the linked list? Is it some random variable that you just declared, or do you think it's one of the pointers you assigned previously? Think about this carefully.

Your previous attempt was almost there except that you were passing the wrong thing to the function. That's it. This latest "revision" has made things far worse.

Last edited by John A; Mar 31st, 2007 at 9:14 pm.

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Re: linked list errors

Apr 1st, 2007

So you need to create a linked list with three nodes and then call a function that follows the links and counts the number of nodes...is that correct?

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Re: linked list errors

Apr 1st, 2007

•

Originally Posted by FC Jamison

So you need to create a linked list with three nodes and then call a function that follows the links and counts the number of nodes...is that correct?

Yes, please..This is what I've come up with now

#include <iostream>
#include <cstddef>
using namespace std;
struct listrec
{
int value;
struct listrec *next;
};

int listsize(listrec*);

int main()
{
struct listrec e1,e2,e3;
e1.value = 4;
e1.next = &e2;
e2.value = 5;
e2.next = &e3;
e3.value = 3;
e3.next = NULL;

int size = listsize(&e1);

cout << "The list size is " << size;

system("pause");
return 0;
}
int listsize(listrec * head)
{

int num=0;
listrec *p = head;
while(*p!=NULL) // producing error
{
*p = *p -> next;
num++;
};

return num;
}

but I'm down to this error:
40 D: no match for 'operator!=' in '*p != 0'

Last edited by maverick786; Apr 1st, 2007 at 1:20 pm.

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Re: linked list errors

#10

Apr 1st, 2007

I have managed to free all compilation errors but when executing the program just terminates with no output except and error
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