Creating a list to hold objects in C++

Question

Forgive me if this seems a bit naive, but I'm rather new to C++ and after years in C and in Java, I guess my head's a little confused.

I'm trying to make an array of an unknown size full of nodes that I've created.

node *aNode = new node(14,32);
std::list<node> dataSet;
std::list<node>::iterator it;
it = dataSet.begin();
dataSet.insert(it, aNode)

However, when I compile this (proof of concept test), it refuses, throwing all sorts of errors.

I know it's something simple and I just can't figure it out. Can anyone help? Thanks in advance!

edit: Here's node:

class node{
    float startPoint;
    float endPoint;
    float value;
public:
    node(float, float);
    void setValues(float, float);
};

node::node(float start, float end){
    startPoint = start;
    endPoint = end;
}

and compiler errors:

error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

error C2371: 'it' : redefinition; different basic types

error C2440: 'initializing' : cannot convert from 'std::list<_Ty>::_Iterator<_Secure_validation>' to 'int'

error C2146: syntax error : missing ';' before identifier 'dataSet'

error C2143: syntax error : missing ';' before '.'

error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

error C2371: 'dataSet' : redefinition; different basic types

update: I changed the little bit of code to:

 node aNode(14, 32);
 std::list<node> dataSet;
 dataSet.insert(dataSet.begin(), aNode);

But these 3 errors remain:

 error C2143: syntax error : missing ';' before '.'
 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
 error C2371: 'dataSet' : redefinition; different basic types

Tiago is right. Declare it as a local variable : node aNode(14, 32); then it should be happy to put it into the list — Graham Griffiths
– Graham Griffiths, Commented Aug 1, 2013 at 16:28
@GrahamGriffiths That didn't help :/ I added the errors and the node class to the main post. — DragonVet
– DragonVet, Commented Aug 1, 2013 at 16:31

PoByBolek · Accepted Answer · 2013-08-01 16:27:17Z

8

Your list should either be of type std::list<node*> or you should insert a node object (and not a pointer to one).

node *aNode = new node(14, 32);
std::list<node*> dataSet;
dataSet.insert(dataSet.begin(), aNode);

or

node aNode(14, 32);
std::list<node> dataSet;
dataSet.insert(dataSet.begin(), aNode);

answered Aug 1, 2013 at 16:27

PoByBolek

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2 Comments

DragonVet Over a year ago

This got rid of a bunch of the errors, but 3 still remain: error C2143: syntax error : missing ';' before '.' error C4430: missing type specifier - int assumed. Note: C++ does not support default-int error C2371: 'dataSet' : redefinition; different basic types

ajp15243 Over a year ago

@user1848437 You might post that as an "update" section of your question for everyone to see easily.

Peter Bloomfield · Accepted Answer · 2013-08-01 16:27:21Z

1

Looks like you need to declare your list to contain node pointers, i.e.:

std::list<node*> dataSet
std::list<node*>::iterator it;

Also worth noting that you can add items to a list without using an iterator:

dataSet.push_back(aNode);

answered Aug 1, 2013 at 16:27

Peter Bloomfield

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Comments

AngelCastillo · Accepted Answer · 2013-08-01 16:28:45Z

1

aNode is pointer to a node object on the heap.

dataSet should be defined as:

std::list<node*> dataSet;

Same with your iterator:

std::list<node*>::iterator it;

answered Aug 1, 2013 at 16:28

AngelCastillo

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Comments

donsiuch · Accepted Answer · 2013-08-01 16:27:46Z

0

For the code you posted your missing a semicolon after the last parenthesis

try

dataSet.insert(it, aNode);

answered Aug 1, 2013 at 16:27

donsiuch

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2 Comments

ajp15243 Over a year ago

Since this may just be a copy/paste error, rather than what's actually being compiled by the OP, it's probably best to ask if the missing ; is in the source code or was a copy/paste error via a comment rather than an answer.

ajp15243 Over a year ago

@user1848437 Might want to edit in a ; to your question then ;)

aamir · Accepted Answer · 2013-08-01 17:47:26Z

0

"missing type specifier - int assumed" can be due to missing

#include <list>

or a missing

#include "header for node"

answered Aug 1, 2013 at 17:47

aamir

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