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Apr 30th, 2008
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Sum in the linked list

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Can anyone please help me to find the sum in the linked list. I have written codes to insert and remove numbers from lists but I have no idea how to calculate the sum.

C++ Syntax (Toggle Plain Text)
  1. void List::insert( const double &value )
  2. {
  3.    ListNode *newPtr = getNewNode( value ); 
  4.  
  5.    if ( isEmpty() ) 
  6.       firstPtr = lastPtr = newPtr;
  7.    else 
  8.    {
  9.       newPtr->nextPtr = firstPtr; 
  10.       firstPtr = newPtr; 
  11.    }  
  12. }
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complexcodes is offline Offline
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Re: Sum in the linked list

iterate through the list until the end of the list.
declare a variable called SUM then add the numbers from each node during the iteration to the variable sum.
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rje7 is offline Offline
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Re: Sum in the linked list

I came up with this codes here :-

C++ Syntax (Toggle Plain Text)
  1. int List::sumOfNodes();
  2. {
  3. 	int sum = 0;
  4. 	Listnode *currentPtr = firstPtr;
  5. 	while( currentPtr ! = null)
  6. 	{
  7. 		sum = sum + currentPtr;
  8. 		currentPtr = currentPtr->nextPtr;
  9. 	}
  10. 	cout<<"The sum is "<<sum<<endl;
  11. }

comipler is showing me errors!
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Re: Sum in the linked list

Click to Expand / Collapse  Quote originally posted by complexcodes ...
I came up with this codes here :-

C++ Syntax (Toggle Plain Text)
  1. int List::sumOfNodes();
  2. {
  3. 	int sum = 0;
  4. 	Listnode *currentPtr = firstPtr;
  5. 	while( currentPtr ! = null)
  6. 	{
  7. 		sum = sum + currentPtr;
  8. 		currentPtr = currentPtr->nextPtr;
  9. 	}
  10. 	cout<<"The sum is "<<sum<<endl;
  11. }

comipler is showing me errors!
copy paste the full code.. lets have a look.
and paste the error messages too if possible.
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rje7 is offline Offline
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Apr 30th, 2008
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Re: Sum in the linked list

well that was my function and I got this error message

1>c:\users\owner\desktop\new folder\list.h(173) : error C2761: 'int List::sumOfNodes(void)' : member function redeclaration not allowed
1>c:\users\owner\desktop\new folder\list.h(174) : error C2447: '{' : missing function header (old-style formal list?)


I called this method in driver :_

listObject.sumOfNodes();

listObject is an object of type List.

am I doing something wrong in function?
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complexcodes is offline Offline
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Apr 30th, 2008
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Re: Sum in the linked list

Here are a few errors I can see
C++ Syntax (Toggle Plain Text)
  1. int List::sumOfNodes();
remove the ';' at the end.

C++ Syntax (Toggle Plain Text)
  1. while( currentPtr ! = null)

null to be written as NULL

C++ Syntax (Toggle Plain Text)
  1. sum = sum + currentPtr;
currentPter is of type Listnode not int. You will have to do something like
C++ Syntax (Toggle Plain Text)
  1. sum=sum+currentPtr->value;

also the function must return a value.
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hammerhead is offline Offline
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Re: Sum in the linked list

here is my updated one but still giving me an error :-
C++ Syntax (Toggle Plain Text)
  1. int List::sumOfNodes() 
  2. {
  3. 	int sum = 0;
  4. 	ListNode *currentPtr = firstPtr;
  5. 	while( currentPtr != NULL)
  6. 	{
  7. 		sum = sum + currentPtr;
  8. 		currentPtr = currentPtr->nextPtr;
  9. 	}
  10. 	return sum;
  11. 	cout<<"The sum is "<<sum<<endl;
  12. }
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complexcodes is offline Offline
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Re: Sum in the linked list

Click to Expand / Collapse  Quote originally posted by complexcodes ...
here is my updated one but still giving me an error :-
C++ Syntax (Toggle Plain Text)
  1. int List::sumOfNodes() 
  2. {
  3. 	int sum = 0;
  4. 	ListNode *currentPtr = firstPtr;
  5. 	while( currentPtr != NULL)
  6. 	{
  7. 		sum = sum + currentPtr;
  8. 		currentPtr = currentPtr->nextPtr;
  9. 	}
  10. 	return sum;
  11. 	cout<<"The sum is "<<sum<<endl;
  12. }

sum = sum + currentPtr;
should be

C++ Syntax (Toggle Plain Text)
  1.  
  2. sum=sum+currentPtr->value; //value=the variable you are using to store the numbers.
sum and currentPtr are of different types.
sum is int and currentPtr->value is an int. but currentPtr is of type ListNode.


after the return statement is encountered the codes after that are inaccessible.
swap the return and cout statements.
Last edited by rje7; Apr 30th, 2008 at 4:01 am.
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Re: Sum in the linked list

I can use same idea to get the average as well?
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Re: Sum in the linked list

Click to Expand / Collapse  Quote originally posted by complexcodes ...
I can use same idea to get the average as well?
hmm..
use another variable called int COUNT to count the number of iterations through the list. that will give the number of nodes.

then float avg=sum/COUNT;

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