i'm currently working on a research project and i've been given some specifications
Is there a way i can access/use the array initialisation list i.e
{value,value,value}; .
For my own class? Like this
myclass foo={value,value,value};
public class Customer
{
public int Id { get; set; }
public string Name { get; set; }
public List<Order> Orders { get; set; }
public Customer() {
Orders = new List<Order>();
}
}
This object is called as
var cust = new Customer
{
Id = 1, Name = "Khatana", [b]Orders.Add(new Order())[/b]
}
I want to ask, Orders.Add(new Order()) is a wrong way, but why..!!... as List<Order> already has been initialized in Customer constructor, then why it is again required to be initialized in object initialization.
Is this a correct way
List<Order> orders = new List<Order> {aaa.....bb....cc};
var cust = new Customer
{
id = 1, Name = "Khatana", Orders = new List<Order> { orders }
}
Why we need to initialize a list in an object initialization, where as the list has been already initialized in object constructor.
I have a class containing a map member that I want to initialize at declaration time. I know I can do it in the cpp file but I'm having a problem with the order of initialization (static initialization order fiasco).
My questions are:
Is it possible that the scenario in which, the Test's constructor's implementation and the map initialization instruction are in the same cpp file and constructor is called when the map is not initialized yet, could happen?
Is it possible to initialize the map in class like I did? I get these errors:
in-class initialization of static data member 'std::map<std::basic_string<char>, Test*> Test::a' of incomplete type
temporary of non-literal type 'std::map<std::basic_string<char>, Test*>' in a constant expression
If yes, does this initialization resolve the static initialization order fiasco?
class Test {
public:
static std::map<std::string, Test*> a = {};//this is an error
Test(std::string ID) {
[Code] ....
I've defined a class with a copy constructor. Some sample code:
Class* c = new Class(*this) // My copy constructor must take in a const Class&
And the compiler gives:
error: cannot convert 'Class' to 'Class*' in initialization
Why does this syntax work with other data types? For example, int* MyInt = new int; compiles fine. What about a copy constructor makes it fail?
Is it possible to initialize class member variables in their definition statement instead of using a constructor?
Is the code bellow correct?
class rectangle
{
float a=0;
float b=0;
public:
string color="Red";
...
};
Which C++ Standard allows it?
I recently discovered the new - new to me anyway! - feature of modern C++ that allows you to set the initial value of a data member when you declare it:
class CINTWrapper{
private:
int m_iData=0;
};
This even extends to calling member functions that work with initialization I believe:
class CStringWrapper{
private:
wchar_t* Allocate_Array(const int iBufferSize);
wchar_t* m_pString=Allocate_Array(1);
};
At first, this seemed an extremely useful piece of functionality that C++ had been lacking all along. However, the more I thought about it the more it struck me this feature actually undermines one of the principle design elements of the language - that being the Constructor.
As I understand it the primary purpose of the Constructor is specifically to give the programmer a place where it is guaranteed he can always initialize his data members before anything else is done with the class. However, given the new initialization rules this is no longer necessary. So it largely seems to me that Constructors as a whole are no longer necessary either! Copy-Constructors are a special and vital case. Admittedly when I was using them for their intended purpose I hated either the redundancy you had to introduce across multiple Constructors; those with and without arguments and so on, or alternately the fine tuning of helper-functions to do common initialization between these variants. Now however I sort of regret this cast-iron rule has been taken away.
As a last point, I am trying to change the way I think about programming. I am trying to employ more objects than pure C-style ('int' or 'double', etc) data types and especially to move into templates (although absolutely NOT the Hewlett Packard template library!). Given my current understanding of inheritance in particular it seems to me that using pre-initialized data members rather than Constructor-initialization makes object derivation even more complicated, not less so.
Code:
class Base {
public:
int base;
Base(int init=0):base(init){}
virtual ~Base(){}
[Code] .....
Invalid initialization of non-const reference of type 'Base&' from an rvalue of type 'Derived'
What does it mean, and why can't I return the Derived class by value (I'm trying to create an exact copy of Derived).
Trying to get code to look like
Row 1: ^^^
Row 2: ^^^
Row 3: ^^^
const int siz = 3;
for (int t=0; t<siz;t++) {
cout << "Row" << t+1 << ":";
cout << endl;
[Code] ....
Also was wondering if i wanted to separately ask the user to choose a location to add a char who would i do that ?
( im thinking * cin << arry[][]; ? not sure but ask for them separately
array []1
array []2
= array [][]
In a book I'm reading, the author has the following struct:
struct VertexPos {
XMFLOAT3 pos;
};
Where XMFLOAT3 is a structure with x,y,z floating point values within. He declares and initializes an array as the following.
VertexPos vertices[] =
{
XMFLOAT3(0.5f, 0.5f, 0.5f),
XMFLOAT3(3.3f, 5.6f, 3.6f),
XMFLOAT3(-4.5f, 2.2f, 6.4f)
};
It doesn't make sense to me why this is working. The way my mind is thinking about this is that vertices is an array of type VertexPos, so then why can it be initialized with objects of type XMFLOAT3?
The following is something I am not clear about. Multi dimensional char arrays and the displaying of them.
Code:
#include <iostream>
using namespace std;
main() {
//char test[5][5]
[Code] .....
The commented out expression didn't run at all but the double quotation mark one did, unfortunately, it gives me a hexadecimal display. How can I get it to display like this:
*****
*****
*****
*****
*****
How do you set all the entries in an array to 0 or a particular number...
View 3 Replies View RelatedI'm having trouble declaring and initializing a two-dimensional array using the C++11 standard conventions. I would like to know how to do it in C++11 style as know how to use the old style.
the exception im getting is:
c++11_array_exp.cpp:37:3: error: too many initializers for ‘std::array<std::array<std::basic_string<char>, 6ul>, 22ul>’
you can find my code here:
[URL]
I've written this class and struct to create a singly linked list. The data is stored in the binary file which I've opened and read. I'm trying to load said data into a class type array. The errors I'm getting are "incompatible types in assignment of 'StatehoodInfo' to char[3]" Lines 130-134 is what I was working on.
#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
#include <string>
#include <cstring> //For char[] string functions
[Code] .....
i have tried like that int arr[1000000] to initialize but it crashed my programm.but if i do int arr[100000] it works fine..why is that and what is the maximum range of integer array initialization??
View 5 Replies View RelatedI have to initialize two arrays with values given alternately from console. But the array takes only the last entered values.
[URL] ....
#include <iostream>
using namespace std;
int main(){
int n,t,i;
cin>>n;
cin>>t;
int a[n];
for(i=0;i<n;i++)
[Code] ....
I am attempting to write a program that converts binary to base10, and vice versa.
But in the function for converting Base10 to Binary, just as it reaches the line of code
int* binary = new int [a];
it skips straight to the int main()
All I'm attempting to do with that line of code is initialize the variable "a" into the elements of the array "binary".
[URL] ....
How can I get the items from a list into textboxes. I am doing an windows form application in visual studio.
I have the first form with a couple of textboxes.
I want the inputs be saved in a list. And then displayed in another form. How to move on. The class with the list looks like this:
public class Casecs {
public List<caseInformation> fallInformation = new List<caseInformation>();
public class caseInformation {
public string caseId { get; set; }
public string phoneNumber { get; set; }
public string description { get; set; }
}
Then the form with the inputs in textboxes looks like this:
Casecs Casecs = new Casecs();
Casecs.fallInformation.Add(new ERIS.Casecs.caseInformation {
caseId = txtCaseId.Text,
phoneNumber = txtPhonenumber.Text,
message = txtMessage.Text
});
Then where I am stuck a form with some textboxes where I want the list items to be displayed:
public partial class btnDispatch : Form {
public btnDispatch() { }
public btnDispatch(List<Casecs.caseInformation> fallInformation) {
InitializeComponent();
I'm trying to develop a program that stores a list of hw assignments in the form of "Date,Assignment name,grade". I have functions that add,remove, and delete from a list, but I would also like to search and delete a particular date found in the list. From here, split - Splitting a string in C++ - Stack Overflow I've tested Evan Teran's method to split a string, but I'm unsure of how to implement it in my code.
List.h Code: #ifndef LIST_H
#define LIST_H
#include <string>
using namespace std;
class List{
[Code] .....
Creating the methods for class List
main.cpp Code: #include "List.h"
int main( )
{
List la; // create list la
la.push_front( "mom" );
la.push_back( "please" );
la.push_back( "send" );
la.push_back( "money" );
la.push_front( "hi" );
cout << "
la contains:
" << la << '
[code]...
I wrote this menu-driven program that maintains a list of restaurants. The program runs fine as it is right now, but my problem is I need to create a new array template class to maintain the list of restaurants, and when a new restaurant is added it must be created dynamically.
I'm having a hard time figuring out what exactly I need to do for this. Templates confuse me allot and I've read all the sections on templates here and in my book, but i'm still lost. The dynamic memory part is throwing me off as well.
main.pp
#include <iostream>
#include <string>
#include <iomanip>
#include "Restaurant.h"
[Code]....
Restaurant.h
#pragma once
#include <iostream>
#include <string>
#include "FTime.h"
using namespace std;
[Code]....
Restaurant.cpp
#include "Restaurant.h"
#include <iostream>
#include <string>
#include <iomanip>
#include <sstream>
using namespace std;
[Code]...
FTime.h
#pragram once
#include <string>
using namespace std;
//class FTime
class FTime {
friend ostream& operator<<(ostream& out, const FTime& obj);
[Code]...
I am trying to use a class Student and declare it as a list type. I can pushback but without changing the List.h or Node.h how can I print the data in list2?
Node.h
#ifndef NODE_H
#defineNODE_H
#include <string>
[Code].....
my data structures and algorithms professor gave us the following assignment. We are to reimpliment a class we wrote earlier in semester called sequence(which holds a sequence of floats) using a linked list. However I am having trouble with the class's copy constructor and assignment operator, specifically when the sequence is not empty.
links to google drive files
node
node header file
test program
sequence implmentation
sequence header file
I'm trying to make an templated class of List and trying to make a list of Students(another class) which I made. Its not working.
Code seems to work fine for pre-defined data types but it crashes when it comes to students. I also want to run sort function on list of students.
how would i access the list created,i should be able to access the list from all other class, adding to it update ect ect.
class test2
{
public string FirstName{ set; get; }
public string LastName { set; get; }
public string Location{ set; get; }
private List<test2> myList = new List<test2>();
public override string ToString()
[code]....
now in a seperate class how would i view the item (print in console) and edit 'mike' location to XYZ.
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.
In this book, item 3 is about never treat arrays polymorphically. In the latter part of this item, the author talks about the result of deleting an array of derived class objects through a base class pointer is undefined. What does it mean? I have an example here,
Code:
class B
{
public:
B():_y(1){}
virtual ~B() {
cout<<"~B()"<<endl;
[Code] ....
This sample code does exactly what I want. So does the author mean the way I did is undefined?