Vector of pointers: some clarification needed

Content Index :

Vector of pointers: some clarification needed
rails 3: clarification needed on which controllers are needed for HABTM relationships
Some clarification needed in the struct pointers
On C++ pointers and references, clarification needed
(C++) Clarification needed about accessing derived functions from a vector of pointers
Pass vector of pointers by reference and replace a vector of void* pointers

Vector of pointers: some clarification needed

Tag : cpp , By : Santhanam

Date : December 01 2020, 04:55 PM

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Vector of pointers: some clarification needed , (C++) Clarification needed about accessing derived functions from a vector of pointers , Some clarification needed in the struct pointers , On C++ pointers and references , clarification needed , vector of pointers c++ ,

rails 3: clarification needed on which controllers are needed for HABTM relationships

Tag : ruby-on-rails , By : OllieDoodle

Date : March 29 2020, 07:55 AM

this will help I think that one way to do it could be the following:
I would accept the event to have the user as a nested resource this way:

class Event < ActiveRecord::Base
    has_many :users
    accepts_nested_attributes_for :events 
end

class ApplicationController < ActionController::Base
  def add_user_to_event
    @event = Event.find(params[:event])
    @user = User.find(params[:user])
    @event.users << @user
    @event.save
  end
end

Some clarification needed in the struct pointers

Tag : c , By : Diego

Date : March 29 2020, 07:55 AM

With these it helps The problem here is that the "->" operator is binding more tightly than the "*" operator. So your first statement:

// what you have written
*root->link;

// what you're getting - bad
*(root->link);

// what you want - good
(*root)->link;

On C++ pointers and references, clarification needed

Tag : cpp , By : Jesse

Date : March 29 2020, 07:55 AM

fixed the issue. Will look into that further
void foo (int &something) // Will accept an address of something

void foo (something); // "something" must be a variable

(C++) Clarification needed about accessing derived functions from a vector of pointers

Tag : cpp , By : user161380

Date : March 29 2020, 07:55 AM

Hope this helps It is hard to follow what exactly do you mean, but I think you refer to automatic allocation getting destroyed. Something among the lines of:

// WARNING: incorrect code
std::vector<base*> v;
for (int i = 0; i < 10; i++) {
  Derived d;
  v.push_back(&d);
}

v[0]->foo();

// WARNING: incorrect code
std::vector<base*> v;
for (int i = 0; i < 10; i++) {
  Derived* d = new Derived();
  v.push_back(d);
  delete d;
}

v[0]->foo();