How can I write my own container which has properties of both vector and list.
E.g. I can access elements directly using [] operator like vector and behave like list in terms of memory (means we don't have to shift elements if we want to insert in between like list)....
I'm working on my first video game. So far I have a few classes in the game starting with the Game class which includes a list of GameObjects (another class). There are several classes that inherit from GameObjects used to implement things like bullets, explosions, various enemy types, etc.
The game essentially iterates through the list of GameObjects to update/render them. I would like to provide access to the Game's list of GameObjects inside another class (like the Bullet class) so I can put new objects on the list. For example, when a bullet hits, I want to add an explosion to the Game's GameObject list it can be updated/rendered.
How this should be setup? I was considering adding a pointer to the Game or GameObject list to the GameObject class (and methods to access it), but I was wondering if there is a better way to set this up?
Unoptimized problem: I work on a table (vector of vectors). vector< vector<double> >
Optimization: If the current set of vectors is v1...vn (so each vk is a vector of double), my problem is such that I will only work on the last M of the vectors, the earlier vectors are irrelevant. I would like to reuse space to make the algorithm scalable, so I want to delete the vectors that can be forgotten. I read in a new vector, I delete the oldest vector.
I am trying to pass a 2D array called f (coming from a text file with 9 columns of numbers and 297,680 rows) that was created using the vector container in my main() to the function myfunc. I'm just trying to figure out how to pass the address of f in main() to myfunc(), so that myfunc() has arguments consisting of a pointer g (that accepts the address of f as an input) and an int.
This is the error from the compiler:
test_2d.cc: In function ‘int main()’:
test_2d.cc:47:25: error: cannot convert ‘std::vector<std::vector<double> >*’ to ‘double (*)[297680][9]’ for argument ‘1’ to ‘int myfunc(double (*)[297680][9], int)’
return myfunc(&f,count);
^
Here is my code:
#include <iostream>
#include <fstream>
#include <iomanip> //allow setprecision to get all the decimal points
#include <vector>
#include <string>
[Code] ...
I will try my best to describe this problem I am having because I am not sure if I can reproduce the error in a small code example as this is part of a large code project.
I have a plain std::vector which contains pointers to objects.
When attempting to delete the objects, even if I know for a fact that the std::vector has at least one object in it as shown by the debugger, I get the "Vector Subscript Out of Range" error.
I'll even do a range for loop like so:
for (auto & e : CurrentObjects) {
delete e;
}
And yet I still get the "Vector Subscript Out of Range" error. The destructor is never called for the object represented by "e" so I am not sure why I get the error.
How would I use the list container to hold a class?
class A {
private : int x;
public : void setX(int val) { x = val; }
};
class B {
private : std::list<A> pdata;
public : void addToList();
};
For adding, I thought of trying something like
void B::addToList() {
A *tmp = new A;
if(A != 0) {
tmp->setX(5);
pdata.insert(tmp);
delete tmp;
}
}
How would I do what I'm trying to do? Or is this the wrong way to go about it? For the actual program, "B" would contain several lists of various classes.
I am making a console based database system. Because I have to keep inserting, editing , deleting data blocks from my record file I have decided to use either vectors or list to store the all records. From the file I shall read the entire vector/list and work with it to add , remove or edit record and then again write the entire vector/list to the file again. I figured it would stop all the weird things that happen when directly working with the file. Is it an efficient way ?Or is it totally unnecessary ?Is there a better way?
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vector<string> words;
words[] = {"one", "two", "three"};
This does not work. How can I accomplish it?
is there any way to copy an entire list to a vector? would make my life much easier
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Do I need to somehow have all the ships in one class. Or are there a way to read the scores from three classes, and adding them up in to one in a new class?
One of the errors I get is "the name 'score1' does not exist in the current context.
I've been attempting to design a multiform WFA in Visual Studio 2010, but I'm so rusty with the language it's hard to remember how to do a lot of things, especially when it comes to visual programming, which my class only partially covered. I've never made a multiform application before, and my problem essentially boils down to how to pass data between forms.
My application is a simple item list and order form, sort of mimicking what you might see on a site like Amazon or eBay. My first form contains a drop down list and 'checkout' button. The dropdown list has been populated with an object collection, each object holding the product's name and price.
public partial class Form1 : Form
{
//Item class for dropdown menu
public class Item {
public string Name;
public decimal Price;
public string itemName
[Code] ....
When the 'checkout' button on form 1 is clicked, I want the Price and Name properties of the selected droplist item to appear in a pair of text boxes on form 2 for the purpose of lowering the user's cognitive load (if they can see what they've selected, it's one less thing to remember).
I've seen plenty of tutorials on how to send a textbox Text property between forms, but none for how to do this. As I said, I'm rusty with the language, and I'm pretty sure there's a better way to set up my combobox items, but I can't remember how to set it up.
Code using auto-implemented property:
public class MyClass {
public int age { get; set; }
}
static void Main(string[] args) {
MyClass testing = new MyClass();
testing.age = 44;
Console.WriteLine(testing.age);
}
output: 44
Code using regular variable declaration:
public class MyClass {
public int age;
}
static void Main(string[] args) {
MyClass testing = new MyClass();
testing.age = 44;
Console.WriteLine(testing.age);
}
output: 44
Why use the auto-implemented property when you can just as equally use the second code block to achieve the same thing?
I had written a "DLL" in VB.NET a year or two ago to read and set MP3 tags. I want to write this exact same library in C++ so I can convert it in my droid project, and to get a hands on introduction to C++. So far this attempt has been a total mind melt!
I am finally wrapping my head around .cpp and .h files so there is light at the end of this tunnel. Here is my problem now:
I wrote the VB project with properties for each tag in the MP3 file, then I could get and set them - easy stuff.
When I try this in C++ I get compile error: a property can only appear within the definition of a managed type. I can usually stumble through Google searches and figure out this type of stuff on my own, but this one is stumping me -- I think I am missing some fundamental stuff here.
My code:
// MP3Tags.h
#pragma once;
#include <string>
using namespace std;
using namespace System::IO;
[Code]....
I have been trying to make a custom control(list box with more features). I know how to setup custom properties, but how do I make it so that the property can be edited in a separate window ?
I think I figured out how to show the form itself, and I don't know how to make the [...] button like :
There's not much Custom Control tutorials out there, and that's really the problem here.
vector<int> vec1 {2, 4, 6, 8, 10, 12, 14, 16, 18, 20};
This code worked perfectly fine in Xcode earlier today, but when I got home on visual studio 2012 express it is having an error. It's saying that the local function definitions are illegal and has a red mark under the '{' only?
I was assigned to print a linked list but as a vector of char (I cannot use the normal string type) , this is what I have:
char* List::asString(){
Node* ite = new Node();
ite= first;//ite is like an iterator of the list
for(int i=0; i<sizeOfList; ++i){//sizeOfList is the total of node of the list
[Code] ....
But when I print that, I get a bunch of weird symbols...
I am making a simple program that is suppose to make a list of champions and their items from the game League of Legends. I am stuck on making a vector of the class so each slot within the vector would hold each champion and its data. This is what I got:
Champion_Info.h
#ifndef CHAMPION_INFO_H_INCLUDED
#define CHAMPION_INFO_H_INCLUDED
#include <vector>
#include <string>
using namespace std;
class Champ_Info
[Code] ....
Well I know how to pass values between forms using get and set properties. But the problem with it is everytime I want to pass values from form2 to form1 it doesn't appear. To make it appear I have to type form1.Show(); which open form1 a second time and then show the value. Is there any way I could make it appear without using form1.Show();?
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I'm trying to get my head around threading and gui applications for fun, and I've ran into a problem I'm not too sure how to google it correctly or I don't understand the answers given. Basically I'm trying to access GUI item properties (add to a listview). I've been on stackoverflow alot, and I've noticed that accessing these properties is quite difficult. At least, I'm not really understanding how it is supposed to be done.
The following line gives me a null value.
frm.lstChat.Items.Add(newList);
From what I understand I need to access my form object instead of creating a new object window... but I'm not sure how to reference the initial form application.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Net.Sockets;
using System.IO;
using System.Threading;
namespace ModBot {
[Code] ....
I have to edit 4-5 lines in the debug, and then 5 lines in release for each of my little project's properties.
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