C++ :: Bit-checking Across Multiple Classes Private Variables
Oct 6, 2013
I am writing a bit-check function just to make it easier on myself to check status flags in my classes. I use char variables and each bit represents something on or off. Since I have numerous classes that will use this functionality, it makes sense to write and compile the code only one time rather than for each class. I was thinking of writing the function and including it as a "friend" function to each class that needs it. Is that an appropriate way to do it?
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Jul 23, 2014
If I want to check if all the variables are pairwise distinct, i.e. they're all different. Here's a code I wrote to do this:
if (s!=e&&s!=n&&s!=d&&s!=m&&s!=o&&s!=r&&s!=y&&e!=n&&e!=d)
if (e!=m&&e!=o&&e!=r&&e!=y&&n!=d&&n!=m&&n!=o&&n!=r&&n!=y)
if (d!=m&&d!=o&&d!=r&&d!=y&&m!=o&&m!=r&&m!=y&&o!=r&&o!=y&&r!=y)
Is there perhaps some function that would let me do this in a lot shorter way, i.e. something like this (that would act the same way my other code does): if (different(s,m,d,e,o,n,y))
What is the best way you can think of? Without having all those variables in an array. Otherwise it wouldn't be so hard to create a function.
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Apr 18, 2013
I need to translate a C program to C by making variables in structures private(no classes yet!) and putting public inline functions. There's a good chance that I have much more problems with my code than I'm asking right now, but I have 4 spots that I'm currently stuck in and can't access properly.
My structures:
Code: struct Container
{
private:
int count;
char** lines;
int nlines;
[Code] .....
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Mar 6, 2015
How to properly pass both private and public variables/functions from one class to another?
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Oct 28, 2014
How would I change the private variables in the header files and the code in the cpp files for the primary indexes so they use a dynamic array or vector instead. For the primary index, the initial vector size will be 8.
header
#ifndef MY_PRIMARY_INDEX_H
#define MY_PRIMARY_INDEX_H
#include
#include
#include
#include
class PrimaryIndex
[Code] ....
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Nov 21, 2013
I'm unable to access private variables belonging to the object class Date, which my overloaded >> operator is a friend of. I can't see anything in my code that would be causing this error. The .h file and the definition of the problematic overloaded operator from the implementation file are below:
#ifndef DATE_H
#define DATE_H
#include <string>
using namespace std;
class Date {
public:
// Initializes a date to the default value of January 1, 1970.
[Code] .....
The error message states that the vars (month, day, year) are declared as private in the header file and then a reference is made to the lines where I attempt to access these in the .cpp file and it reads: "in this context".
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Sep 19, 2014
I've been working on a program that uses a reference counting class that I've written which works fine for objects that inherit from it however I now need to have the following setup:
class SBComponent : private Refcounted { /*stuff*/}
class ProxiedComponent : public SBComponent, private Refcounted {/*stuff*/}
The compiler gives the following warnings
warning: direct base ‘Refcounted’ inaccessible in ‘ProxiedComponent’ due to ambiguity
And then several repeats of the error:
error: request for member ‘bk’ is ambiguous
Back *b = bk<ProxiedComponent>();
bk is a templated function that's defined in Refcounted and returns a pointer of type <template arg>::Back (ProxiedComponent::Back in this case).
I don't understand why the call to bk is ambiguous as although there's two instances of Refcounted (there needs to be with the way I've designed it so I can't make it virtual) it's inheritance is private in both cases so there should only be one instance of it visible in ProxiedComponent.
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Feb 23, 2014
im creating an address book. One address book contains a ListBox, New User button, Edit User and Remove User button. The first form is suppose to allow you to view the users you've created on the ListBox and you can decide whether you want to remove it, create a new one or simply edit the user. Now The second form simply contains labels and textbox along with a save button. I'm having a bit of issue figuring out the ListBox. I want to be able to create a user and have the user be posted on the ListBox. I read that i must instantiate listbox then simply add it. Now on my form2 i have a for loop that loops through an Array of String were all the users will be created on. How can i call that array of string on to the form1?
Form 1:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
[code].....
EDIT:I just figured out that to call a variable from one form to another you simply instantiate the form then simply call it. PS. must be set to public:
ListBox1 createUser = new ListBox1();
createUser.userString[0];
why doesnt it show the windows when i run without debugging?
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Mar 1, 2013
If I have a static variable in a class e.g. a pointer to another class like this: (B is another class)
class A {
public:
static B* cB;
};
Then I set that variable and create multiple instances of class A like this:
A::cB = new B;
As = new A[Number];
Then will the value of cB be the same across all instances?
I cannot pass the class pointer in the constructor as I need to create an array of instances. I tried this method but I get linker error.... unresolved external.
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Apr 2, 2014
I am wondering how to share a variable in 3 classes. For example:
variable class:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
[Code] ...
class that edits the variable:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
[code]......
The actual program:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
[code]......
What should happen when this runs is this:
Variable changed in program: 0
Same variable changed in a different class: 1
Instead, this happens:
Variable changed in program: 0
Same variable changed in a different class: 0
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Apr 6, 2013
Is it possible to overload a variable in a derived class? Example:
struct Circle
{
int radius() const { return r; }
private:
int r;
}
struct Smiley : Circle
{
// inherits the function int radius() const, but doesn't return Smiley::r
private:
int r;
}
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May 20, 2013
I want to make a basic RPG text based games with multiple classes. but I wan to know how In one class I make a variable and in another and can call the variable.
for exmaple
class2:
int hi = 1;
class1:
class2 a;
hi = 2;
cout << hi;
2
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Oct 12, 2014
When I set a local variable to a value it causes a segmentation fault. This happens in the GameObject class in the setGame method.
While your at it tell me what you think of the design. Am I on the right track? if not state why.
Here is the source: [URL]
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Sep 24, 2014
We typically don't bother with massive, monolithic code files that get processed from top to bottom. In the Object Oriented world, code files don't mean much. In fact, in C#, I could have multiple classes defined in one file, or have one class split across several files.
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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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May 20, 2013
Instead of using:
Code:
x=x+k
y=y+k
z=z+k
Is there a more elegant method of adding the same constant to many variables?
Something like: Code: (x, y, z) = (x, y, z) + k ??
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Jan 19, 2014
I am trying to get variables that are global to multiple files. I have mananged to make constant variables that are global but maybe not in the best way. In the header i have the constant variables being defined:
const int variable_Name = 5;
And the cpp file:
#include <iostream>
using namespace std;
#include "vars.h"
int main ( ) {
cout << variable_Name<< endl;
system ("pause");
return 0;
}
Is there a better way to do this and to make the variables able to be changed within the cpp files.
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Oct 22, 2013
I am trying to return 2 numbers from my function to main(). They are both read in from an input file but it is not working out.
#include <fstream>
#include <iostream>
using namespace std;
ofstream outfile;
void heading(int);
int stuid(int,int);
[Code] ....
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Aug 1, 2012
I would like to create an array of struct variables inside a table to avoid using many if/else and/or switch/case statements. I have attached a simple example of what I am trying to do, it doesn't work. For the table "sTablePtr" I see different values than what I set, when I dereference it with a "&" it just shows me the addresses of the variables. However at the end, when I do print out the values, by just using the structs themselves, they print out the values correctly.
My structure declarations must remain a pointer. To be clear, what I am trying to do is have sTablePtr[i] show me the correct values I set, in this case I want the for loop to print out 1, 2 and 3. If there is a different way of doing this, I am open to it as long as I can use a table of my struct variables to avoid many if statements.
#define MAX_CNT 3
typedef struct {
int nNum;
int nCnt;
}sDummy1;
[Code] ....
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May 6, 2013
So I have this text file that I am trying to read from and store the values of each line in multiple variables. Let's say my text file contains
AXSYZ3482 Tom 100 112 and my code below here works fine when the lines in the text file is separated by spaces.
Code:
while (fscanf(fp, "%s %s %d %d
", userID, name, &startLoc, &endLoc) != EOF) {
printf("%s %s %d %d
", userID, name, startLoc, endLoc);
}
But let's say my file was to look like this instead.
AXSYZ3482:Tom:100:112
But if i try this below...
Code:
while (fscanf(fp, "%s:%s:%d:%d
", userID, name, &startLoc, &endLoc) != EOF) {
printf("%s %s %d %d
", userID, name, startLoc, endLoc);
}
It seem to store the entire line in userID including the ":". I want to ignore the ":"'s and store everything in between in respective varibles in the order specified above.
So first string in userID, then ignore the :, then second string in name, and ignore the next :, and so forth.
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Sep 3, 2013
I want to put my socket programming example of how it can support multiple ports. I want to make the process more requests from distributing particles to create non-blocking structure
ports support ports defined variable.
Code:
#include "stdio.h"
#include "stdlib.h"
#include "unistd.h"
#include "errno.h"
#include "string.h"
#include "sys/socket.h"
[Code] .....
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May 6, 2013
So I have this text file that I am trying to read from and store the values of each line in multiple variables.
Let's say my text file contains
AXSYZ3482 Tom 100 112
and my code below here works fine when the lines in the text file is separated by spaces.
while (fscanf(fp, "%s %s %d %d
", userID, name, &startLoc, &endLoc) != EOF) {
printf("%s %s %d %d
", userID, name, startLoc, endLoc);
}
But let's say my file was to look like this instead.
AXSYZ3482:Tom:100:112
But if i try this below...
while (fscanf(fp, "%s:%s:%d:%d
", userID, name, &startLoc, &endLoc) != EOF) {
printf("%s %s %d %d
", userID, name, startLoc, endLoc);
}
It seem to store the entire line in userID including the ":". I want to ignore the ":"'s and store everything in between in respective varibles in the order specified above.
So first string in userID, then ignore the :, then second string in name, and ignore the next :, and so forth. How I can accomplish this?
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Oct 5, 2013
I have an array of (Student)classes created in Manager.h, which contains a new instance of class Name (name),(in Student.h)How would I go about accessing the SetFirstName method in Name.cpp if I was in a class Manager.cpp? I have tried using Students[i].name.SetFirstName("name");
// In Manager.h
#include"Student.h"
class Manager
{
[Code]....
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Jul 31, 2014
I want to develop an application which can host multiple views of explorer (window), where as each window is totally separate from others. So that I can have multiple desktop views through my single explorer. Any built in feature in .NET ?
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Aug 17, 2014
how to make subroutines and return multiple arrays.Before that, i wrote my program on matlab. could my program to be structured as following?
<header>
initial value of program;
subroutine1() {
calculating the first work;
return 2 or 3 arrays;
[code].....
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Sep 19, 2013
I usually check if a bit is set using:
Code: bit = (number >> n) & 1; where `n` is the bit I want to check...
But I came across a stackoverflow answer saying:
bit = number & (1 << x); will not put the value of bit x into bit unless bit has type _Bool (<stdbool.h>).
Otherwise, bit = !!(number & (1 << x)); will..
So why is this? why the double !?
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