I'm working on a project involving nested classes and structs like this:
Code: class A {
public:class B {
public:f()
{A::C* iCanDoThis; //no errors.
iCanAlsoDoThis->root->.... //this also works fine.}private:A::C* iCannotDoThis //this is what I would like to do.
Has errors
A* iCanAlsoDoThis;};private:struct C
{..data..};
C* root;};
Is it possible make a pointer to struct C a private member of class B?
I wanted to ask if it is somehow possible to do:
Code:
class RaspberryPi: public Singleton<RaspberryPi> {
private:
static const DeviceInfo GPS;
template<typename Register_t>
auto ReadGPS(Register_t& Register) -> void
[Code] ....
There are two limitations I am facing:
First, it seems that anything that is part of a struct cannot be a compile-time expression. It's a nice way to group information, so it would be nice to have.
Secondly, it seems that all compile-time expressions cannot be inside a class (at least according to VC++), which means I have to move them to global level, but while it can be done, I don't really want to do it, because it's a platform detail.
In this case, static type dispatch would be nice to have because I have a function
Code:
template<typename Register_t>
auto ReadBus(Platforms::DeviceInfo Device, Register_t& Register) -> void {
switch (Device.Bus)
[Code] .....
There are two types of registers. With runtime dispatch, I get disgusting errors such as "could not deduce template arguments, blah blah" if some object doesn't have the required interface (i.e., don't have overloads for both register types). So the workaround would be to add two overloads and use something like asserts to stop invalid code from running, but it would be so nice to only allow correct code to compile and not get scary error messages.
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.
how I would execute a nested class in a linked list... As example;
[Character][Weapon][Spell] classes are children of a [Base] class that stores normalized information such as 'Name'...
I am aiming to have a unique Character with a unique Weapon and Spell. I am trying to link-list these to have multiple characters. I just can't apply the design logic into programming logic.
cNode.h
#pragma once
#include "Includes.h"
class cNode
[Code]....
I have a program to make a contact book. Included below i will post both header files and cpp files of my contact book, my contact class, and my address class. and my main.cpp. The reason address and contact are separate was because my teacher had us do an exercise where we used a header file of someone else's code, and didn't know what the functions actually implemented. But as the project has progressed he gave us the cpp for address.
Main.cpp
#include "Address.h"
#include "ContactBook.h"
#include "Contact.h"
[Code].....
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?
"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?
I am having a lot of trouble being able to get data from a file and input it into given structs and arrays of structs and then outputting the file. We are given a file that contains 96 lines and looks like this:
Arzin, Neil
2.3 6.0 5.0 6.7 7.8 5.6 8.9 7.6
Babbage, Charles
2.3 5.6 6.5 7.6 8.7 7.8 5.4 4.5
This file continues for 24 different people and then repeats with different scores (the second line).
The first number, in this case is 2.3 for both people is a difficulty rating. The next 6 numbers are scores.
We are given this data in order to set up our structs and arrays and my code:
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <cmath>
using namespace std;
int main () {
ifstream inFile;
inFile.open("C://diveData.txt);
[Code] .....
I wrote this code, and everything was working well, but part of the assignment is that it must include nested loops. Once I added the nested while loop, which is basically an if statement, my life was ruined. I am trying to nest a loop in the code that will basically tell the compiler that if the value "loopVol" were to exceed the value of "final" after adding an increment, to run the program for the "final". How can I do that?
Example:
initial = 10
final = 123
increment = 10
as of now, the program would stop at 120, but I want to nest a loop that will tell the compiler to calculate at the final if this happens.
#include <iostream>
#include <iomanip>
#include <stdio.h>
[Code]......
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]....
If i want to input (FROM A FUNCTION) information into a struct:
* How do I define/ call/ prototype that function.
* How do I check if that array inside the function is empty?
What the second print statement prints
main() {
struct s1{
char *str;
int i;
struct s1 *ptr;
[Code] .....
I executed the code and the output was some number(for second printf) but it should print a string.
The main is not working properly, I get strange missing parenthesis notices and array errors which I am not understanding. How to identify the errors. Functions are included.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int menu ();
double change_value (double * value);
[Code] ......
I'm currently working on a program that writes an array of struct to a file and then read back the data from the file to another array of struct. At the bottom is an image of my result.
My goal is to end up with two identical struct arrays but my program fails to do this. My struct have to members: ID and kind (of animals in this case). I declare my first arraystruct africa[] with "monkey" and "giraffe" with their respectively IDnr: 112 and 555. I stream this data to a file and read read them back to the arraystruct get_animal[]. Simply I want the get_animal[] to be identical with the africa[] when the program is over, but that is not so. According to my result(bottom image) it display:
112, monkey (get_animal[0])
112, monkey (get_animal[1])
meaning that get_animal[0] is identical to africa[0] get_animal[1] is also identical to africa[0]
but why? I want get_animal[1] to be identical with africa[1]. meaning I want the result to look like this:
112, monkey
555, giraffe
I've also made the program to print the parameters of my fwrite/fread calls. Why is the 3rd parameter = 1 meaning that only 1 element will be read/written when my program just read/write 2 elements?
Code:
main(){
FILE *fp;
struct animals
{
int id;
char kind[20];
} africa[1] = {{112,"monkey"}, {555,"giraffe"}};
}
[code]....
How would I be able to have this display the rest of the households without having to have 13 separate cout lines(one for each household)? In other words, how can I set it up to increment the output?
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
struct Household {
int idNumber;
int income;
[Code] ....
I think i am getting confused with passing structs and functions all in the same...When I run through the program (it compiles), the functions that add coins do not add, but rather just replace an old value with a new one.
#include <cstdlib>
#include <iostream>
using namespace std;
struct coinbox {
[code].....
I can't seem to remember everything I should about constructors. I'm looking for a way to create an array of structs, using a constructor. My code should explain.
struct myStruct
{
private:
int structInt1, structInt2;
[Code].....
What I'm trying to do :
struct foo {int x; int y;};
foo function_example(int x, int y) {
foo temp;
temp.x = x;
temp.y = y;
return temp;
}
Works as is, however when I try doing it through seperate class files :
//header file for class example_class
struct foo {int x; int y;};
foo function_example(int x, int y);
//source file for example_class
foo example_class::function_example(int x, int y) {
foo temp;
temp.x = x;
temp.y = y;
return temp;
}
I get an error telling me that foo is undefined, and that declaration of function_example(int x, int y) is incompatible with the declaration of it in the header file.
I have an assignment where I need to use pointers to do a few things and I am a little confused on the syntax of it all. My question is how do you use a pointer to point to an array of structs.
For example
struct info{
char firstName[15];
char lastName[15];
};
main() {
info person[4];
cout << "The third letter of the second persons first name is: "; // ?????
}
how would I define a pointer to point to the third letter of first name the second person in the "person" array.
How to fill a vector with structs that are read in from a separate file. Each line in the file would read for example "Doe John M 26" for the name of the person, gender and age. I just need to get pointed in the right direction so I can get this started.
View 2 Replies View RelatedWhat is the difference between reading from binary file between the following way:
struct aStrct{
int number;
}vars[];
while(file.good())
file.read((char*)&vars, sizeof(aStrct))
And
while(file.good())
file.read((char*)&vars[i], sizeof(aStrct))
i++;
Write a program for the following problem. You're given a file that contains a collection if IDs and scores (type int) for an exam in your computer course. You're to compute the average of these scores and assign grades to each student according to the following rule:
If a student's score is within 10 points (above or below) of the average, assign a grade of satisfactory. If a studnt's score is more than 10 points above average, assign a grade of outstanding. If a student's score is more than 10 points below average, assign a grade of unsatisfactory.
The output from your program should consist of a labeled three-column list that shows each ID, score, and corresponding grade. Use a struct to store each student's data and an array of structs to store the whole class. The struct should have a data member for id, score, and grade.
I was given the following file grades:
3313904258647075100
568888487970797094
4700504489737073100
956188698887846398
31999669100908867100
376878578059571560
82917256708274983
7754766293100784158
81469468999493954
2106984796947027100
So far, I have this much, but the output is all wrong. I also haven't tackled the grade part yet.
Code:
//grader.cpp
//Grades
#include <fstream>//required for file streams
#include <iostream>//input/output
#include <cstdlib>//for definition of EXIT_FAILURE
#include <string>
#include <iomanip>
using namespace std;
#define inFileGrades "grades.txt"//grades
[code]....
I am versed in qsorting struct members within a struct instance, as in the example below:
Code:
#include <iostream>
#include <stdlib.h>
using namespace std;
struct item_database {
[Code]....
What I CANT do however is to sort an array of structs by one of its members. This is a complete different problem even if it sounds similar.
In other words, the problem is this; Say we have a struct:
Code:
struct item_database {
int key;
string token;
};
Then we declare an array of this struct in the heap:
Code: item_database *idptr = new item_database[700000]; and initialize its values.
How would one go about sorting this heap array of structs by its member function "token"?
I used the following call to qsort (standard library) and call to the compare function but it doesnt work:
Code:
qsort (idptr, 1000, sizeof(string), compare);
Code: int compare (const void* a, const void* b){
if (*(char*)a >= *(char*)b)
return 1;
else
return -1;
}
Or in more lamens terms say we have the following stuct instances:
Key: Token:
1 Hello
2 World
3 How
4 Are
5 You
Then I need those structs to order according to token (alphabetically, increasing or decreasing depending whats in our compare function).....
what I am trying to do is to pass to a function the address of an array of structs, so I can later modify the items within the struct, within the array
Code:
typedef struct { //A struct of name auctionint bidder;float bid;} auction;
void myFunction (auction * auctionItem[]){(*aucItem[x]).bid = y;(*aucItem[x]).bidder = z;}
int main(){auction theItems[10];
myFunction(theItems);} Where x, y, and z can be any number.
When I try to run my code the IDE (I'm using Code::Blocks 12.11) does not give me any errors, but it does give me a warning:
warning: passing argument 3 of '<function name>' from incompatible pointer type [enabled by default]
and the note:
note: expected 'struct <struct name> **' but argument is of type 'struct <struct name> *'.Also, when I run the program, it will crash and return garbage.
I have a structure product_array *pa that contains a pointer *arr to an array of structs and count that adds 1 when a new product is added (set to NULL initially). I have to write a function which adds a new product entry to that array. One product entry has *title, *code, stock and price parameters. The array is dynamically allocated and I’m supposed to:
1. Reallocate space for array.
2. Update product_array.
3. Initialize it.
Also, code should be truncated to 7 characters.Products can be added multiple times, so the initial size is unknown.
Code:
void add_product(struct product_array *pa, const char *title, const char *code, int stock, double price)
{
for (int i = 0 ;; i++){
pa->arr = realloc(pa->arr, sizeof(struct product_array));
[code]....
I have a struct and I want to implement in with pointers and functions.
What is the corect syntax? For example:
Code:
typedef struct XYZ
{
int x;
int y;
int z;
}XYZ_t;
int func( using the XYZ_t struct)
[Code] .....