C/C++ :: Why And Where To Use Nameless Object
Mar 24, 2013why we use this object and what purpose we use it
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C/C++ :: Pointer To A Nameless Structure
Sep 16, 2014const free_throws & clone(free_throws & ft) {
free_throws * pt;
*pt = ft; // Copy info
return *pt; // return reference to copy
}
This is a code snippet extracted from C++ Primer Plus book. However, it is really confusing. I don't really understand the free_throws * pt;
as far as I know, a pointer has to point to a memory address, and it is best to initialize it when it is declared. However, according to the code snippet above, the pt isn't initialized to any address. Isn't it dangerous when we declare a pointer without initializing it before we use it?
I thought it is supposed to be like this
free_throw * pt = new three_throw;
// or
free_throw * pt = & ft;
BTW, free_throw is a structure.
C++ :: Will Copy Constructor Does Object Initialization Using Another Already Created Object
Mar 16, 2013will copy constructor does object initialization using another already created object? I understand that it can be applied for object initialization and not for assignment.Is it correct?
View 10 Replies View RelatedC# :: Method Is Overwriting Both Instance Of Object And Original Object
Jul 3, 2014I have a method to take a Tile object and make an instances of it based on some data from the original object. Than it is suppose to manipulate the a specific instance and save the results. The first loop through it works but it changes all instance as well as the base.
public static int recurse(int count, Tile[,] b,Huristic h,int check) {
if (check==1) {
boardState.Add(B)/>;
return check;
} if (check == 0)
[Code] .....
C++ :: Importance Of Static Object In A Class And How They Are Different From General Object
Dec 13, 2012#include "B.h"
class A {
public :
A()
{
s_b = new B();
b = new B();
[Code] ....
In my project i have seen static object as above . But not able to know what is the exact use of it and how they are different from general object .
C++ :: What Can't Non-const Object Receive Temporary Object
Sep 11, 2014a function returns a temporary object like
int myfun(){
int x = 0;
return x;
}
this function will return a temporary integer now void fun1(const int & num); this function can receive from myfun().BUT void fun2(int & num); this function cannot receive from myfun() Why is that, Moreover what is lifetime of a temporary object like one returned in myfun() ???
C# :: Constructor Object Reference Not To Set Instance Of Object
Mar 28, 2014I am trying to use web api in order to return custom json response keys. For this i have return a custom class to return json response
Custom Class:
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
[Code].....
C Sharp :: Object Reference Not Set To Instance Of Object?
May 4, 2013I have a combobox with Items 1024
2048
4096
8192
String cach = form.comboCache.SelectedItem.ToString();
I am using the above code to retrive an item selected by user,But this line is giving an exception "Null Reference Exception, Object reference not set to an instance of an object"
C# :: Object Reference Not Set To Instance Of Object?
Mar 28, 2014I am using session to pass object from controller to custom class in MVC Web API. here is my code, i am getting error at session.
public HttpResponseMessage Get()
{
var person = db.Persons.ToList();
[Code]....
C/C++ :: Get Reference To Text Object With The Name Of Object?
Aug 23, 2013In Visual Studio 2010 C++
I have a series of existing text objects
The text properties names are
item1_lbl,
item2_lbl,
item3_lbl,
….
Based on a selection I want to change an object. I generate the name of the object I want to change in a string so from this string is there a way to get a pointer to the correct text object that is same name?
C++ :: Starting Vertex Array Object At Index Of Vertex Buffer Object
Sep 22, 2014I'm trying to figure out how I can create a vertex array object at offset of a vertex buffer object.I've created the buffer object. I'd like the "texs" idnex data to start at the texture coordinate content of the vertex_t structure.
Type definitions:
struct vertex_t {
vector3d_t position;
float s; // Texture coordinate s
float t; // Texture coordinate t
};
Code so far:
// How do I make this start at a certain spot of the VBO?!
glVertexAttribPointer(texs, 2, GL_FLOAT, GL_FALSE, sizeof(vector3d_t), nullptr;
//...
C++ :: How To Get Object Of Original Class From Function Of Other Class Where Other Class Object Is Member Of Original Class
Jan 21, 2013The case is like
class B{
public:
somedata;
somefunction();
}
class A{
public:
data;
function();
}
in somefunction i want a pointer to current object of class A m new to c++
C :: How To Create An Object
Oct 31, 2013I have an assignment that asks me to implement a variant of the classic bouncing balls program.
'Each ball should start off at the top of the screen with a random speed in the x direction. Whenever a ball hits a screen boundary it should bounce off at an angle equal to the impact angle and lose some speed. Eventually each ball should come to a rest at the bottom of the screen. Five seconds after coming to a rest a ball should be removed from the screen.'
'Your code must keep track of objects (balls) by placing the object data structures in a linked list. You need to create your own linked list implementation. Below is a brief description of the object programming interface: CreateObject - Create a new object. The function accepts as input parameters a pointer to the SDL screen, a pointer to a model triangle array, and a variable telling the size of the model triangle array. The function returns a pointer to a new object data structure. The model triangle array specified as input parameter should not be shared across objects. (Not sharing the model triangle array allows e.g. objects to have different colors.)
Perform the necessary memory allocation and copying.DestroyObject - Free object. The function accepts as input parameters a pointer to an object data structure. The function should free all memory allocated to represent the object (memory allocated for the model triangle array and the object data structure itself).
Drawobject - Draw object on screen. The function accepts as input parameters a pointer to an object data structure. The function must draw the object on the screen by calling DrawTriangle on each of the model triangles. Remember to update scale, translation, etc., in each triangle data structure before invoking DrawTriangle.
Hint: Do not make the bouncing algorithm too complex. Bouncing a ball off a vertical or horizontal surface can be accomplished without resorting to calculating impact angles.'
The function I'm stuck at, is the first one - createobject.
My first aim is to get one ball on the screen.
Code:
// Create new object
object_t *CreateObject(SDL_Surface *screen, triangle_t *model, int numtriangles)
{
object_t *object = malloc(sizeof(object_t));
object->model = malloc(sizeof(sphere_model));
object->screen = SDL_Surface;
memcpy(*model, object->model, sizeof(object_t));
return object;
// Implement me
}
This is what I've done so far.
C++ :: How To Use Object From Another Class
Dec 21, 2013I have two classes one called Date and the other is University , Date class has two overloaded operators , ostream and istream to take in the data and print them out :
ostream & operator<<(ostream & out, Date & x) {
out<< x.month << "/" << x.day << "/" << x.year ;
return out;
[Code] ....
The University class has an object of type Date called establishDate and I must use this to print out the date along with the University name and location, here's University class :
University.h
class University {
public:
University (); // constructor
friend ostream & operator<<(ostream & out, University & x); // print the university data
friend istream & operator>>(istream & in, University & x); // to read university data
[Code] .....
so how do I use the establishDate object ?
C++ :: Getting A Type From Object
Apr 20, 2013it is not possible to get a type from an object, only from a type. Even with auto, you can only instantiate another type of the same type.I'd like to get a type from an object given another type, mainly because it is less typing and less error prone.
Some psudocode:
Type1 A<X, Y> a;
int b;
Type2 a.InnerType<b>::type c; // obviously won't work
A work around I thought of would be to use functions:
Type1 A<X, Y> a;
int b;
auto c = a.getInnerType(b);
Which is kinda interesting and looks like the way I'm going to go. However, I'm just wondering if there is any other ways of doing this as I don't really want to instantiate an object if I can avoid it (though the optimizer will probably just dump it anyway).
C++ :: How To Link An Object To Another One
Jun 27, 2013I have the following problem, I have an object of a class Subject, and I want that this object points to another object of class Classes, creating a kind of link. How can I do that?
View 4 Replies View RelatedC++ :: Object Variables Going To NaN
May 26, 2014So I am trying to develop a sort of 2d spacesim engine for creating games in C++. The project uses SFML for graphics, and I am currently trying to compile it on Linux using g++.
The main issue that I am wrestling with is that of simulation objects having their position, velocity, and rotation variables constantly getting set to NaN for reasons that are beyond me. The behaviour is not consistent, and occasionally will occur or not occur without any discernible pattern.
The github repo for the code is here: [URL] ....
I understand that NaN values can spread easily by operations on one another, but I cant seem to figure out where the initial issue is occurring here.
C++ :: How To Get Object Name In The Constructor
Mar 11, 2013is it possible to get object name in the constructor? I would like to initialize an object of circle class without any arguments and put some pretty lines in constructor to get and save as table of chars the name of creating object. Is it possible? I work with MSVS2012.
View 4 Replies View RelatedC++ :: Cannot Delete Object
Apr 18, 2014int NextPixel(int antIndex, int currentPixel , Ant *ant , IplImage *edgeImg) {
int left = currentPixel - 1 ;
int right = currentPixel + 1 ;
int up = currentPixel - edgeImg->widthStep ;
int down = currentPixel + edgeImg->widthStep ;
[[Code] ....
if those lines are uncommented , program gives heap error.Why?
C++ :: How To Return Another Object Value
Nov 8, 2014How can I return other object's value in a function(see code and comments)?
Person.h
Code:
#include <iostream>
#include <string>
using namespace std;
class Person{
public:
Person();
Person(string pname, int page);
[Code] ....
C++ :: Trying To Pass Array Of Object
Apr 24, 2013I am trying to pass an array of objects however i m finding some problems.
pieces.h
Code: class Cpiece{
public:
Cpiece* board[8][8];// array of objects
virtual char getcolor() =0;
virtual char setcolor(char colour)=0;
[Code] .....
C++ :: How To Attach A Char To Each Object
Apr 23, 2013I am trying to make a game in c++, I have an array of object however i m facing a problem to see which player is playing. i need to attach a value to each object such as 'w' what this is called and what should i do im, new to c++ programing....
View 3 Replies View RelatedC++ :: Moving Object In Array
Nov 30, 2014I want to make an object in array[][] move
Ex:
array[2][5]
array[0][0] = 'O'
O| | | | |
| | | | |
| | | | |
then
|O| | | |
| | | | |
| | | | |
then
| |O| | |
| | | | |
| | | | |
......
how can i print my array in console then change&print it again, then change&print it again,... So it look like O is moving
???
C++ :: Check For Clicks Within Object
May 21, 2013Writing this code that handles clicks with the left mouse button. But I want to be able to check for clicks within a 200x200 pixel area. Here's what I have:
void EGame::OnLButtonDown(int mX, int mY) {
int ID = mX / 200;
ID = ID + ((mY / 200) * 3);
if(grid[ID] != GRID_TYPE_NONE) {
[Code] .....
Using the width and height of the object, e.g; pX->w is width and pX->h is height ....
How would I check within the 200x200 area with mX and mY?
C++ :: Calling All Instances Of Object?
May 28, 2013So I am wondering how I would go about calling a function for all instances of an object. I tried googling it, but all I saw was solutions like making an array of pointers to the objects. What if I don't know how many objects there will be? Isn't there an easier way?
View 19 Replies View RelatedC++ :: Sorting Of Object In A Vector
Oct 24, 2013I'm new to C++ especially vectors.. I've a question regarding sorting of object in a vector.. My object consists of x,y and civ. so I would like to know how do I sort the value of the civ in an descending order but at the same time retaining the value of x and y attached to it..
original
X: 4 Y: 5 CIV: 10
X: 3 Y: 2 CIV: 30
X: 3 Y: 3 CIV: 05
sorted
X: 3 Y: 2 CIV: 30
X: 4 Y: 5 CIV: 10
X: 3 Y: 3 CIV: 05
missionplan.cpp
void MissionPlan::topfives() {
stable_sort (topfive.begin(), topfive.end());
pointtwoD = topfive.at(i);
pointtwoD.displayPointdata();
}