C++ :: Nested Class Vector Index Access?
Mar 22, 2014
Is it possible to pass the vector index '4' to the Height() function without passing it as a parameter of the function.
Basically, I'm trying to eliminate using 4 twice... what I'd LIKE the statement below to look like is this:
gx.Cell[4].Height();
The only way I can figure out how to get it to work is like this...
class grid{
public:
class CELL{
public:
int Height(int index); //returns the height of this cell
[Code] .....
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Jul 12, 2013
It's hard to give a precise title but here is the question in detail: I have a class, something like this:
Code:
class classA{
public:
void fnA();
...
};
and another class that contains objects of classA:
Code:
class classB{
public:
classA A1;
classA A2;
classA A3;
vector<classA*> vA;
...
};
classB B1;
Now is it possible to access B1.vA from B1.A1.fnA() through some kind of pointer chain like this->parent->vA ? If so
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Jan 22, 2015
I need to know how to access the nested structure using pointer, i mean i know how to do that when i have simple structure, for example:
Code:
struct person{
char fname[16], lname[16];
int age;
}
for this example i can use
Code: (*pointer).age
or
Code: pointer->age
But if i have structure like this:
Code:
struct date{
int day, month, year;
}
struct person{
char fname[16], lname[16];
struct date birthDate;
}
Then how can i access the birthDate using pointer?
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Nov 26, 2013
I have a nested record structure in C++ that contains a FileHeader record, a RecordHeader record and a DataRecord record. The last item is an array of unknown size (at compile time). I have to open a file and read the array size and then create the array.
I have worked on this for some time and can't figure out how to make it work. I know the sample data I am using has 85 records. I insert 85 into the array size and it works fine. But how do I create a dynamic array or define a vector within a nested structure?
1. What is the best (easiest) method to accomplish this (array or vector)?
2. How would it be implemented/how do you add data to it?
PreviousLogRecord.FaultRecord.push_back(field1); // does not work
PreviousLogRecord.FaultRecord[recordNumber].field1 = somedata; // works with 85 in array size.
struct LogFileHeaderRecordType {
QString field1;
int field2;
[Code] .....
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Sep 9, 2013
if we don't provide the acces modifiers for base class and we need to manipulate the private data of base class in derived class. Is there anyway to acces the private data members? Here's a coding example
class A {
private :
int a;
};
class B : public class A {
public :
void displayA() { cout<<a<<endl; }
};
how i can acces the a of base class A in derived class B without acces modifiers.
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May 1, 2015
so lets assume i have a nested vector in a set or vice versa o in a more general form a container in a container example...
Code:
std::set<vector<int> > my_tuple;
How do i access individual elements of lets say the first vector in the set! Or the last element in the 3rd vector?
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Oct 7, 2014
How to initialize a static member of a class with template, which type is related to a nested class?
This code works (without nested class):
#include<iostream>
using namespace std;
struct B{
B(){cout<<"here"<<endl;}
};
template<typename Z>
[Code] ,....
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May 3, 2013
I am storing info in a vector but I want to store certain info at a particular index. I am new to using vectors and am unsure about have to do this. I am aware of the insert method but am confused on how to use it to store at a particular index.
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Jun 30, 2014
I have vector of keyframes for animation:
struct Keyframe {
float time;// time in seconds
...
};
std::vector<Keyframe> vKeys;
And every loop i accumulate delta time to animate my object:
update(float deltaTime) {
timeRunning += deltaTime;
const float animationLen = 5.0f; // 5 seconds is total length of animation
...
To calculate current Key/index into vector i use:
float currTime = std::fmod(timeRunning, animationLen);
m_currKeyFrameInx = std::size_t(vKeys.size() * currTime / animationLen);
... use index
Can this logic fail?
Before i was using this:
float currTime = std::fmod(timeRunning, animationLen);
m_currKeyFrameInx = 0u;
for (std::size_t i = vKeys.size(); --i;) {
if (vKeys[i].time < currTime) {
m_currKeyFrameInx = i;
break;
}
}
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Dec 2, 2014
how to check if a specific index equal to null when i try to implement it, it gives an error for example:
vector < vector <double> > v;
v[0].push_back(0);
v[0].push_back(1);
v[0].push_back(2);
v[0].push_back(3);
v[1].push_back(10);
v[1].push_back(11);
v[1].push_back(12);
v[1].push_back(13);
if(v[0][4]==NULL) {
cout<<"empty"<< endl;
}
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Jan 20, 2014
So I have this problem with not being able to iterate over a vector in a nested for-loop. Here's the nested for-loop:
bool innerHit = false;
for (std::vector<Sprite*>::iterator outerIter = sprites.begin(); outerIter != sprites.end() && (!sprites.empty()); outerIter++) {
Sprite* spriteOne = *outerIter;
for (std::vector<Sprite*>::reverse_iterator innerIter = sprites.rbegin(); innerIter != sprites.rend() && (!sprites.empty()); innerIter++) {
Sprite* spriteTwo = *innerIter;
[Code] .....
What happens is, after having called the collisionDestroy-function and the program tries to execute the nest loop in the outer for-loop, it all crashes with the text "Expression: vector iterator not decrementable", which I understand is because the iterator will have already become useless. The question is: know this, how do I fix it? I can't seem to get a hang of it.
Here's the collisionDestroy-function (the collisionReaction does nothing but sets a few local variables):
void Enemy::collisionDestroy(std::vector<Sprite*>& sprites) {
for (std::vector<Sprite*>::iterator iter = sprites.begin(); iter != sprites.end(); iter++) {
Enemy* tmp = dynamic_cast<Enemy*>(*iter);
if (this == tmp && collisionType == 3 || collisionType == 1) {
sprites.erase(iter);
break;
}
}
}
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Jun 26, 2013
I initialized a nested vector with the following code as:
Code:
vector<vector<Point> > vectorB(4, vector<Point> (int(vectorA.size()), 0));
And came across the following error during link stage:
"/usr/include/c++/4.6/bits/stl_vector.h:1080:4: error: no matching function for call to ‘std::vector<cv::Point_<int> >::_M_fill_initialize(std::vector<cv::Point_<int> >::size_type, int&)’ "
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Jul 17, 2013
this is the first time to ask my question on Cplusplus. my qustion is i got this message when i trying to run this code:
object.h
#ifndef __NCTUNS_nslobject_h__
#define __NCTUNS_nslobject_h__
#include <stdio.h>
[Code].....
so, my problem is when the compiler starts compiling it stops on this code :
NslObject::newKeyPair (RSA::GenerateKeyPair(keyLength));
and the appeared message is :
Error:
object.cc: In function ‘void Set_KeyPair()’:
object.cc:53: error: no match for call to ‘(KeyPair) (KeyPair&)’
so, how could i assign a generated keypair class value to NslObject::newKeyPair.
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Nov 9, 2013
Consider the following program below, which compiles without a hitch on MinGW GCC 4.8.1:
template <typename T>
class Outer {
class Nested1 {};
template <typename U>
class Nested2
[Code] .....
Is there any way I can move the definition of func outside of the class?
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Jan 16, 2013
it seems that I cannot define a method of an inner nested class if it is a private class. for example:
class outter {
class nested {
void foo ( void ) {} // okay - but is this inline?
} void inner::foo( void ) {} // not okay - cannot define inside another class
} void outter::inner::foo( void ) {} // not okay - 'nested' class is private!
what I want to know is, is there another way to define an inner class's method? and if not, is it eternally doomed to be inline because it has to be declared inside it's own class declaration?
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Jun 25, 2014
I am having problems invoking methods in a nested class using reflection. I have the following:
A parent class, Group, that holds instances of a simple class called Signal. I want to modify the number of instances inside the group class often. So, all my code has to be dynamic and use reflection to know how many instances of signal there are inside the Group class.
class Group{
public static Signal name1 { get; set; }
public static Signal name2 { get; set; }
public static Signal name3 { get; set; }
[Code]....
I had no luck invoking the method of the instances of signal class that are inside the Group class. I tried getting the methods name using getMethods() but could not navigate through the syntax.
How could I invoke and pass parameters to the method of the instances of signal using reflection? Is there a better way of accessing the properties and methods of nested classes?
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Jan 7, 2014
I need an implementation for the array index operator overloading of my Fraction class . The Fraction.h looks like :
#include <iostream>
using namespace std;
class Fraction {
public:
Fraction(int = 1, int = 1);
[Code] .....
I am not able write the Array index operator overloading functions.
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Jan 20, 2013
I have the following code which will find the minimum size queue among a vector of queues and the minimimum size queue will enqueue(push) the int
std::vector<std::queue<int> > q
void enqueue(){
int min_index = 1;
std::size_t size = q.size();
for( i=2; i<size; i++) //accessing loop of queues
if(q[min_index].size() > q[i].size())
min_index = i; // Now q[min_index] is the shortest queue
q[min_index].push(int)
}
Now my another paradigm is to do the dequeue(pop) operation in another function(shown below), bt i need to access all vector of queues declared in enqueue() function. how can i access the loop of queues given in the enqueue() function?
void dequeue(){
//q.pop operation , access all the queues in the loop of queues
}
willq[i].pop(int);
Access all the queues in the enqueue function and does the pop operation?
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Aug 4, 2013
How to access an element of the point3f vector. E.g. :
int main() {
vector<Point3f> a;
a.push_back(Point3f(0,0,0);
a.push_back(Point3f(0,0,1);
//print first x,y,z element
cout<<a[0]<<endl;
[Code] ...
But it doesn't work firstly because it says can't use typename i.e. <float>
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Sep 4, 2014
So I have an ImageManager class, Board class, and Box class. In Board.h I can declare ImageManager imgr; and in Board's constructor I can use imgr and its functions and such. However, in Box.h when I try and declare ImageManager imgr; I get the error "cannot access member declared in class ImageManager". Both declarations are under private, and exactly the same, but one doesn't work. Also, is there a way to only have one instance of ImageManager?
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Nov 9, 2013
I am trying to access a variable from another class through another class but it is not returning its "instance"?
Example:
Class View
Code:
...
V3D_Viewer viewer;
...
Class MainWindow
Code:
...
viewer* myView;
myView = new viewer();
...
Class Test
Code:
...
MainWindow window;
window.myView->setBackgroundColor(WHITE);
...
I am new to c++ references and pointers,
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Feb 22, 2013
I have two classes, a Package class and a Person class. The Package class has two Person objects has member variables, a Sender and a Receiver. While overloading the << operator for the Package class so that it will make an output label from everything in the Package class. Here is my code...
class Package{
public:
Person Sender;
Person Reciever;
int weight;
double cost;
friend ostream &operator<<(ostream &out, Package &pack);
[Code] .....
So my problem is on that last output line, I am unable to call Sender.getName()... etc. Is there a proper syntax so that I can access the members of the Person class while overloading the << operator for the Package class?
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Jan 19, 2014
I need to access the functions of the derived classes from a vector of objects of base classes (can't believe I wrote it). Here a Diagram for you to understand:
So as you see, I need the function Use() from the Usable class, to be able to be called from the vector like:
inventory.at(x)->Use()
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May 18, 2013
"A nested class has free access to all the static members of the enclosing class. All the instance members can be accessed through an object of the enclosing class type, or a pointer or reference to an object."
How can the members be accessed through an object of the enclosing class type? I understand the pointer and reference part because for them you dont need the full definition, but for creating a object you do?
Also it has free access to all static members because the nested class is part of the enclosed class and with static it exists in everything inside the enclosing class? Right or am I missing something?
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Apr 23, 2013
I cannot wrap my head as to how to access my enum class Azimuth.
Code: #ifndef BOUSOLE_H
#define BOUSOLE_H
#include <iostream>
#include <string>
#include "StringHandler.h"
class Bousole{
[code]...
And here is where I am trying to access my enum for testing/understanding purposes
Code: #include "Bousole.h"
using namespace std;
int main (int argc, char *argv[]){
cout <<"Start bousole" << endl;
Bousole b;
[Code] ....
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May 13, 2013
I need to create a class vector as a template and define operations on vectors.
And this is what I made.
#include<iostream>
using namespace std;
template<class T>
[Code].....
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