#include<iostream>
#include<string>
using namespace std;
class Item{
private:
string type;
string abbrv;
string uID;
int aircraft;
double weight;
string destination;
public:
Item(string t, string a, string u, int aC, double w, string d){
type = t;
abbrv = a;
uID = u;
aircraft = aC;
weight = w;
destination = d;
}
Item(){}
Item(Item & i){
type = i.type;
abbrv = i.abbrv;
uID = i.uID;
aircraft = i.aircraft;
weight = i.weight;
destination = i.destination;
}
void print(){
cout << "ULD: " << type << endl;
cout << "Abbreviation: " << abbrv << endl;
cout << "ULD-ID: " << uID << endl;
cout << "Aircraft: " << aircraft << endl;
cout << "Weight: " << weight << " Kilograms" << endl;
cout << "Destination: " << destination << endl;
}
friend void kilotopound(Item);
};
void kilotopound(Item I){
cout<<"Weight in Pounds: " << I.weight * 2.2 << " LBS " << endl;
}
bool operator == (Item &ab, Item &bc){
if((ab.a == bc.a) && (ab.u == bc.u)){
return true;
}
else{
return false;
}
}
int main(){
Item I ("Pallet", "PAG32597IB", "PAG", 737, 3321, "SEA");
I.print();
kilotopound(I);
cout << "\nCopy\n\n";
Item I2(I);
I.print();
kilotopound(I);
cout<<"\nSecond Object\n\n";
I2.print();
kilotopound(I2);
Item unit1 ("Pallet", "PAG32597IB", "PAG", 737, 3321, "SEA");
Item unit2(unit1),unit3(I);
if (unit1 == unit2)
cout << "\nUnit1 and Unit2 are the same \n";
else
cout << " \nUnit1 and Unit2 aren't the same \n";
if (unit2 == unit3)
cout << " \nUnit2 and Unit3 are the same\n";
else
cout << " \nUnit2 and Unit3 aren't the same\n";
return 0;
}
Hi! So the code above gives me the error 'class Item' has no member named 'a' at line 46, which is where to bool operator is. Can someone help me out with basically just trying to get the code to function and explain why I get the error even though I have the data made public?
I'm pretty lost at why this happens even if the abbreviations are already stated. Also I tried just using abbrv and uID but got an error that the data was private.
Thank you!
a is the parameter of Item's constructor Item(string t, string a, string u, int aC, double w, string d), not an "alias" of Item::abbrv. Constructors are functions, and the parameters of a function are only available inside the function body.
There is no "member alias" in C++, nor is there any concept of "properties" (like in C#). To provide read-only access to Item::abbrv, define a "getter" function for it:
// Public member function of class Item:
const string& getAbbrv() const {
return abbrv;
}
Related
#include <iostream>
#include <list>
#include <iterator>
using namespace std;
class Profesor
{
public:
string nume, departament;
int grad, vechime;
Profesor(string n, string d, int g, int v);
};
Profesor::Profesor(string n, string d, int g, int v) {
nume = n;
departament = d;
grad = g;
vechime = v;
}
int main()
{
list <Profesor*> profi;
Profesor* p;
int opt;
string nume, departament;
int grad, vechime;
do {
cout << "1.Adaugare" << endl;
cout << "Dati optiunea! " << endl;
cin >> opt;
switch (opt)
{
case 1:
cout << "Nume:";
cin >> nume;
cout << "Departament:";
cin >> departament;
cout << "Grad:";
cin >> grad;
cout << "Vechime";
cin >> vechime;
p = new Profesor(nume, departament, grad, vechime);
profi.push_front(p);
default:
break;
}
} while (opt);
return 0;
}
Option 1 is to add a new item into the list
This is the constructor of the class
So I need a function to display the entire list
ajgnsjdgn afkajkf nskjfnakfakfnaf afnakfnasdnlang akfnafdakfrnaasf asdfkasfna
ad akjdgnakjsgsa askfnaksd asgnaskdng asdgjnsadgag
Add a function to Profesor to output it's current variables:
void output() const {
cout << " * nume: " << nume << endl;
cout << " * departament: " << departament << endl;
cout << " * grad: " << grad << endl;
cout << " * vechime: " << vechime << endl;
}
Create a function that iterates through the list and calls this function.
Here is an example that uses a range based for loop:
void outputProfesors(const list<Profesor*>& profesors) {
for (const auto& profesor : profesors) {
profesor->output();
}
}
Call outputProfesors().
I am relatively new to C++. I am hoping to get assistance creating an overload operator that will permit me to use a literal string with a class I am writing. This project is for learning.
I created a custom Date class (and have not worried about the actual logic in the class; I'm just trying to get the interface working and to understand where my roadblock is.
It may not look like it, but I have put in a lot of time on this, so an explanation designed for a beginning c++ progammer would be very helpful to me and anyone who follows in my footsteps.
Basically, I'd like to be able to do this with my class:
Date dt(5,6,92);//create class object
int myint;
myint = dt;//this works
string mystr;
mystr = dt("mm/dd/yy");//this does not compile
Thanks in advance. (A compilable test program shown below)
#include <iostream>
#include <string>
#include <windows.h>
using namespace std;
class Date
{
int mo, da, yr;
public:
Date(int m, int d, int y)
{
cout << "Constructor int m, int d, int y called " << endl;
mo = m; da = d; yr = y;
}
string getdatestr(const char *s = "") {//user sends in format "d2/" "mm/dd/yy" etc
cout << "getdatestr const char *s called mo = " << mo << " da = " << da << "yr = " << yr << endl;
return to_string(mo) + "/" + to_string(da) + "/" + to_string(yr);
}
int getdate(){
cout << "getdate int t called" << endl;
string tag;
tag = to_string(yr) + to_string(mo) + to_string(da);
return stoi(tag);
}
string getdate(string &str){
cout << "getdate with string as ref" << endl;
return "5/5/55";
}
int getdate(int &myint){
cout << "getdate with int as ref" << endl;
return 12345;
}
void setdate(string dt){
cout << "setdate string dt called " << dt << endl;
mo = 1;
da = 2;
yr = 2020;
}
void setdate(int intdte){
cout << "setdate int to " << intdte << endl;
mo = 99;//any int for now
da = 98;
yr = 1997;
}
void setdate(const char *dte){
cout << "setdate char* dte = " << dte << endl;
mo = 94;
da = 95;
yr = 1996;
}
~Date(){
cout << "destructor called" << endl;
}
//below code permits this in main(): myint = dt;
operator int() {
cout << "operator int()" << endl;
string tag;
tag = to_string(yr) + to_string(mo) + to_string(da);
return stoi(tag);
}
//end section to permit: myint = dt;
//what do I need so I can do this: mystr = dt("mm/dd/yy");, nothing below worked; I tried many more iterations
//than what are shown here
/*
operator string() {
cout << "operator string char" << endl;
return "hello world";
}
string operator = (string &rhs){
cout << "string" << endl;
return "return a string";
}
operator = (const string &rhs){
cout << "will this work?" << endl;
return *this;
}
char& operator = (char(&)[9]){
cout << "whoa, it worked" << endl;
//return "got it";
}
operator = (char*){
cout << "try again" << endl;
}
string operator const char(&)[9] {
cout << "one more time" << endl;
string *ptr;
ptr = "one more time";
return ptr;
}
//end nothing worked to permit me to do this mystr = dte("mm/dd/yy"); section
*/
};//end of class
int main()
{
//create a Date class object dt
Date dt(5, 6, 92);
dt.setdate("02/15/22");
cout << endl;
cout << "next two mystr messages return null because I " << endl;
cout << "can't seem to write a valid overload operator for a literal string" << endl;
string mystr;
//mystr = dt("mm/dd/yy");//does not compile (no match for call to '(Date) (const char [9])'
cout << "mystr using dt(str) = " << mystr << endl;
string myconv = "mm/dd/yy";
//mystr = dt(myconv);//does not compile (no match for call to '(Date) (std::__cxx11::string&)'
cout << "mystr using dt(mm//dd//yy) = " << mystr << endl;
cout << endl;
//this section works
//can I assign dt to an integer (as #days from a reference date)
cout << "this section seems to work" << endl;
int myint;
cout << "myint = dt;" << endl;
myint = dt;//does not compile
cout << "myint (using = dt;) = " << myint << endl;
cout << endl;
system("pause");
}
I have a class of light bulbs. There are methods and constructors in this class. There is even a destructor) The problem is that I have to determine and display information about class members with type "n" in the TEST() method (LED lamps).
To implement this task, he developed the gettype() method, which returns the type of an object, and, in fact, the TEST() method, which displays information about light bulbs.
The problem is that nothing works for me. I tried a lot of things, but it doesn’t work out for me to implement this task. I'm new to programming (
Code:
#include <iostream>
using namespace std;
class lamp
{
public:
// methods
void TEST(void);
char* gettype (void);
void INIT(void);
void SHOW(void);
// construcrors
lamp();
lamp(const char *t, int powe, const char *c, double cos);
lamp(const lamp & obj);
// destructor
~lamp();
private:
// data
char type[100]; // LED, energy-saving or incandescent lamp
int power; // LED lamp - "n"
char color[100];
double cost;
};
lamp::lamp() {
cout << "This object was created in the default constructor.\n";
strcpy(type, "");
power = 0;
strcpy(color, "");
cost = 0;
}
lamp::lamp(const char *t, int powe, const char *c, double cos) {
cout << "This object was created in the constructor with parameters.\n";
strcpy(type, t); //*t
power = powe;
strcpy(color, c); //*c
cost = cos;
}
lamp::lamp(const lamp & obj) {
cout << "This object was created in the copy constructor.\n";
strcpy(type, obj.type);
power = obj.power;
strcpy(color, obj.color);
cost = obj.cost;
}
lamp::~lamp() {
cout << "Deletion of object by destructor.\n";
}
void lamp::SHOW(void) {
cout << "Lamp Information:\n";
cout << "\nType > " << type;
cout << "\nPower > " << power;
cout << "\nColor > " << color;
cout << "\nCost > " << cost << endl;
}
void lamp::INIT(void) {
cout << "Enter lamp information:\n";
cout << "\nType (if LED, then n) > "; cin >> type;
cout << "\nPower > "; cin >> power;
cout << "\nColor > "; cin >> color;
cout << "\nCost > "; cin >> cost;
}
char* lamp::gettype (void) {
return type;
}
void lamp::TEST(void) {
cout << "\nType > " << type;
cout << "\nPower > " << power;
cout << "\nColor > " << color;
cout << "\nCost > " << cost << endl;
}
void main() {
setlocale(0, "");
// default constructor for 1 class instance
lamp l1;
cout << "Entering data for the first product." << endl;
l1.INIT();
// constructor with parameters for 2 class instances
cout << endl << "Information about the second object: \n";
lamp l2("n", 950, "yellow", 1580);
// copy constructor for the third object
cout << endl << "Information about the third object: \n";
lamp l3(l2);
// Derived information about all the lamps using the method SHOW
l1.SHOW();
l2.SHOW();
l3.SHOW();
// I create an array of two objects using the default constructor
lamp la[2];
I enter data into an array of objects using the method INIT
cout << "Fill an array of objects with 2 elements." << endl;
for(int i = 0; i < 2; i++) {
la[i].INIT();
}
// I output data from an array of objects using the method SHOW
cout << "Showing items." << endl;
for (int i = 0; i < 2; i++) {
la[i].SHOW();
}
// looking for and displaying information about LED lamps
cout << "Search and display information about LED lamps." << endl;
for (int i = 0; i < 3; i++) {
if (la[i].gettype() == "n") {
cout << endl << " lamp number : " << (i + 1) << endl;
la[i].TEST();
cout << endl;
}
}
system("pause");
}
There are several errors in your code：
strcpy is included in <cstring> which is missed. You need to add it in the beginning:
#include <cstring>
main() function should be declared as int main() and you need to add a return statement
int main() {
//YOUR CODE HERE
return 0;
}
You missed a comment sign at line 104
lamp la[2];
//I enter data into an array of objects using the method INIT
cout << "Fill an array of objects with 2 elements." << endl;
After fixed, your code should be able to run.
Take a look at the initialization list of the derived class in the code below.
class city {
private:
int id;
int x;
int y;
public:
int getID(){return id;};
int getX(){return x;};
int getY(){return y;};
city(){
id =0; x=0; y=0;
}
city(int idx, int xx, int yx){
id = idx;
x = xx;
y = yx;
}
city(city* cityobj){
id = cityobj->id;
x = cityobj->x;
y = cityobj->y;
}
};
class city_detail : public city{
private:
city* neighbor;
public:
city_detail (city& neighborX, city& cityobj): city(cityobj){ // What???
/* ^ city(cityobj) and city(&cityobj) both work here */
neighbor = &neighborX;
}
city* getN(){return neighbor;}
};
int main(int argc, char*argv[]){
city LA(42, 1, 2);
city PDX(7, 3, 4);
city_detail LA_Detail(PDX, LA);
cout << "LA_Detail.ID: " << LA_Detail.getID() << endl; // works both ways
cout << "LA_Detail.x: " << LA_Detail.getX() << endl; // works both ways
cout << "LA_Detail.y: " << LA_Detail.getY() << endl; // works both ways
cout << "LA_Detail.NN: " << LA_Detail.getN() << endl; // returns address as it should
city * LA_neighbor = LA_Detail.getN();
cout << "LA_neighbor.ID: " << LA_neighbor->getID() << endl; // address is indeed valid
cout << "LA_neighbor.x: " << LA_neighbor->getX() << endl; // address is indeed valid
cout << "LA_neighbor.y: " << LA_neighbor->getY() << endl; // address is indeed valid
return 0;
}
Why is it that both ...: city(&cityobj) AND ...: city(cityobj) work here?
I would think that I cannot do the latter, ...: city(cityobj), and that I must pass in an address to cityobj since the base class' constructor takes in a pointer.
Why am I not getting some compile error such as:
cannot convert type city to city * ?
Clearly, I am not able to do this in other places, such as:
void getID(city* aCity){
cout << "aCityID: " << aCity->getID() << endl;
cout << "aCityX: " << aCity->getX() << endl;
}
void wrapper(city &aCity){
getID(&aCity); // I must pass in the address here, else I get an error
}
city Greenway;
wrapper(Greenway);
The reason it works is that when you call city(cityobj) it uses the compiler's implicitly defined copy constructor, and when you call city(&cityobj) it uses the converting constructor you defined yourself: city(city* cityobj).
You didn't mean to say neighbor(&cityobj) did you?
I have a class A:
class Sportist{
private:
string ime;
int godina_na_ragjanje;
int godisna_zarabotuvacka_EUR;
public:
Sportist(string i, int g_n_r, int g_z_EUR){
ime = i;
godina_na_ragjanje = g_n_r;
godisna_zarabotuvacka_EUR = g_z_EUR;
}
string getIme(){
return ime;
}
int getGodinaNaRagjanje(){
return godina_na_ragjanje;
}
int getGodisnaZarabotuvackaEUR(){
return godisna_zarabotuvacka_EUR;
}
};
And class B using the class A as public:
class Fudbaler:public Sportist{
private:
int broj_na_odigrani_natprevari;
int danocna_stapka;
public:
Fudbaler(string ime, int godina, int zarabotuvacka, int b, int d)
:Sportist(ime, godina, zarabotuvacka)
{
broj_na_odigrani_natprevari = b;
danocna_stapka = d;
}
float danok(){
return getGodisnaZarabotuvackaEUR() * danocna_stapka;
}
friend ostream& operator<<(ostream &os, Fudbaler F){
return os << "Ime: " << getIme() << endl
<< "Godina na raganje: " << getGodinaNaRagjanje() << endl
<< "Godisna zarabotuvacka(EUR): " << getGodisnaZarabotuvackaEUR() << endl
<< "Danok sto treba da plati: " << danok();
}
};
And I get 4 errors as described in title in these lines:
return os << "Ime: " << getIme() << endl
<< "Godina na raganje: " << getGodinaNaRagjanje() << endl
<< "Godisna zarabotuvacka(EUR): " << getGodisnaZarabotuvackaEUR() << endl
<< "Danok sto treba da plati: " << danok();
cannot call member function 'std::string Sportist::getIme()' without object
cannot call member function 'int Sportist::getGodinaNaRagjanje()' without object
cannot call member function 'int Sportist::getGodisnaZarabotuvackaEUR()' without object
cannot call member function 'float Fudbaler::danok()' without object
i would say the function should be changed to
friend ostream& operator<<(ostream &os, Fudbaler F){
return os << "Ime: " << F.getIme() << endl
<< "Godina na raganje: " << F.getGodinaNaRagjanje() << endl
<< "Godisna zarabotuvacka(EUR): " << F.getGodisnaZarabotuvackaEUR() << endl
<< "Danok sto treba da plati: " << F.danok();
}
I am not shure about operator overloading for the std::streams. i usually have done that outside of the class. From your error messages, you need to use the passed Fudbaler variable to access the methods of it.