C++ creating a class object [closed] - c++

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Closed 10 years ago.
I am having issues creating an object for my class, I am getting errors trying to create the class object with the defined data members.
// class header for employee
#pragma once
#include <string>
#include <iostream>
class Employee
{
private:
std::string name;
int empnum;
std::string address;
std::string phone;
double hourwage;
double hoursworked;
public:
Employee(void);
Employee(int, std::string , std::string, std::string, double, double);
double gethourwage () const;
double gethoursworked () const;
double printcheck () const;
std::string getphone() const;
std::string getname() const;
std::string getaddress() const;
};
// end of header
// employee class.cpp
#include "Employee.h"
#include <string>
#include <iostream>
Employee::Employee(void)
{
int empnum = 0;
double hourwage = 0.0;
double hoursworked = 0.0;
}
Employee::Employee(int num, std::string nme, std::string addres, std::string phon, double hourpay, double hrswrked)
{
num = empnum;
nme = name;
addres = address;
phon = phone;
hourpay = hourwage;
hrswrked = hoursworked;
}
double Employee::gethourwage() const
{
return hourwage;
}
double Employee::gethoursworked() const
{
return hoursworked;
}
double Employee::printcheck() const
{
double pay = 0.0;
double hrspay = hourwage;
double hrswork = hoursworked;
return hoursworked;
}
// end of employee.cpp
// main
#include <iostream>
#include <algorithm>
#include <numeric>
#include <vector>
#include <iterator>
#include <string>
#include "Employee.h"
using namespace std;
int main( )
{
int num1 = 10210;
double hourwage = 20.2;
double hourworked = 32.3;
string steve;
Employee emp(num1, steve, 58s200w, 90210, hourwage, hourworked);
cout << "" << emp.getaddress();
system("PAUSE");
return 0;
} // end of main
"Employee emp(num1, steve, 58s200w, 90210, hourwage, hourworked);" towards the bottom is the line I am having the issue with. I am not sure if I am entering it in the wrong order, or something else.
Thanks in advance for any help.

You should enter strings in double quotes:
Employee emp(num1, "steve", "58s200w", "90210", hourwage, hourworked);
Edit 1 (tried to explain the difference between const char * and std::string, as #Alex suggested)
Literal strings in the snippet above are of type const char *, which is a low-level entity inherited from the C language. const char * is a pointer to memory area which holds consecutive values of type const char.
std::string is a higher-level wrapper around C-style strings intended to provide more «user-friendly» API and solve some problems of C-style strings (e.g., dynamic allocation and automatic memory cleanup).
Because the std::string class has a constructor which takes a const char * parameter, literal strings passed to the Employee constructor are implicitly converted to std::string's

Your Employee class constructor is
Employee::Employee(int num, std::string nme, std::string addres, std::string phon, double hourpay, double hrswrked)
and you are calling it as
Employee emp(num1, steve, 58s200w, 90210, hourwage, hourworked);
You can directly see the difference, Employee class constructor expecting 2nd, 3rd and 4th argument as String. So you have to pass these arguments as string. Either you have to declare string as hourwage, hourworked variables as you defined or you have to pass arguments as nameless above explained.

Related

No declaration matches in Codelite IDE

I have been looking in different threads with this error which is quite common but it feels like the IDE I am using messed with my workspace and I can't quite find the problem. I am setting up an extremely basic class called "Movie" that is specified below:
Movie.hpp :
#ifndef MOVIE_HPP
#define MOVIE_HPP
#include <iostream>
#include <string>
using std::string, std::cout,std::size_t;
class Movie
{
private:
std::string name;
std::string rating;
int watched_ctr;
public:
Movie(const string& name, const string& rating, int watched_ctr);
~Movie();
//getters
string get_name() const;
string get_rating() const;
int get_watched() const;
//setters
void set_name(string name);
void set_rating(string rating);
void set_watched(int watched_ctr);
};
#endif // MOVIE_HPP
Movie.cpp:
#include <iostream>
#include <string>
#include "Movie.hpp"
using std::string, std::cout,std::size_t,std::endl;
Movie::Movie(const string& name, const string& rating, int watched_ctr)
: name(name) , rating(rating) , watched_ctr(watched_ctr) {
}
Movie::~Movie()
{
cout << "Destructor for Movies class called /n";
}
//Getters
string Movie::get_name(){return name;}
string Movie::get_rating(){return rating;}
string Movie::get_watched(){return watched_ctr;}
//Setters
void Movie::set_name(std::string n){this -> name = n;}
void Movie::set_rating(std::string rating){this -> rating = rating;}
void Movie::set_watched(int ctr){this -> watched_ctr = ctr;}
The main.cpp I am trying only consists in creating one Movie object:
#include <iostream>
#include <string>
#include "Movie.hpp"
using std::string, std::cout,std::size_t,std::endl;
int main()
{
Movie StarTrek("Star Trek", "G", 20);
}
As you can see, I set all the attribute to private in order to exercise with the set/get methods but I keep stumbling upon the same error on each of them stating >"C:/Users/.../ProjectsAndTests/MoviesClass/Movie.cpp:18:8: error: no declaration matches 'std::__cxx11::string Movie::get_name()"
if you could give me a hint on what might cause this error I would greatly appreciate thank you!
I tried opening another workspace with classes implemented inside of them and the syntax I am using is very close from this test workspace I opened which compiled fine (no error regarding declaration match).
There are 2 problems with your code.
First while defining the member functions outside class you're not using the const. So to solve this problem we must use const when defining the member function outside the class.
Second, the member function Movie::get_watched() is declared with the return type of string but while defining that member function you're using the return type int. To solve this, change the return type while defining the member function to match the return type in the declaration.
//----------------------vvvvv--------->added const
string Movie::get_name()const
{
return name;
}
string Movie::get_rating()const
{
return rating;
}
vvv------------------------------>changed return type to int
int Movie::get_watched()const
{
return watched_ctr;
}
Working demo

Why is my Code runing under codeblocks but not in VS Studio

This line canot pass under VS Studio, But it is running under CodeBlocks.
cg1.RegisterGoods("c++", 23, 32);
'void CGoods::RegisterGoods(char [],int,float)': cannot convert argument 1 from 'const char [4]' to 'char []'
like so:
#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include <cstring>
using namespace std;
class CGoods
{
private:
char Name[21];
int Amount;
float Price;
float Total_value;
public:
void RegisterGoods(char name[], int amount, float price)
{
strcpy(Name,name);
Amount = amount;
Price = price;
}
void CountTotal(void)
{
Total_value = Price * Amount;
}
void GetName(char name[])
{
strcpy(name,Name);
}
int GetMount(void)
{
return Amount;
}
float GetPrice(void)
{
return Price;
}
float GetTotal(void)
{
return Total_value;
}
};
int main() {
CGoods cg1;
cg1.RegisterGoods("c++", 23, 32);
cout<<cg1.GetPrice()<<endl;
cout<<cg1.GetMount();
return 0;
}
char name[] as a function parameter is equivalent to char *name while your string literal has a type const char [4] which can only be (safely) converted to const char *, so you have to change your parameter like this:
void RegisterGoods(const char *name, int amount, float price)
and here:
// Renamed to SetName given that it's what this function actually does
void SetName(const char *name)
In general though you shouldn't use plain char arrays to store strings in C++, you should instead prefer using std::string:
std::string Name;
...
void SetName(std::string name)
{
// take advantage of move semantics to avoid redundant copying
// if you are using C++11 and beyond
Name = std::move(name);
}
Don't use c-constructs for things, c++ has better answers. char-pointers can lead to unwanted behaviors and nasty buffer overflow exploits and so on. It is far better to use a std::string.
Change your member-function RegisterGoods to:
void RegisterGoods(std::string const & name, int const amount, float const price)
{
Name = name;
Amount = amount;
Price = price;
}
and your declaration of Nameto:
private:
std::string Name;
your return function GetName to:
std::string GetName() const
{
return Name;
}
OR
void GetName(std::string & name) const
{
name = Name;
}
also add the include for std::string:
#include <string>
Tip for a better code... don't use using namespace std. std is a enormously huge namespace. Unintentionally you may override a function out of std and you end up with a nearly undebuggable error.
Also define your parameters in setter functions as const, so you can't change the value of it unintentionally.
Is that means that we don't need strcpy and char in c++ anymore? Because i replaced all the 'char' with string and its funktion also. like this:
private:
std::string Name;
public:
void RegisterGoods(const string name, int amount, float price)
{
Name=name;
Amount = amount;
Price = price;
}
const std::string GetName()
{
return Name;
}

C String assigning values in explicit constructor in C++?

I have a class BankAccount with two string members - name and num. What I want is to assign values to these objects when I create them (when the constructor is called). However the compiler says No instance of constructor matches the argument list when I try to create an object.
I would like to ask why is that?
// hwk-2.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#include "pch.h"
#include <iostream>
#include <string>
#include <stdio.h>
using namespace std;
class BankAccout {
char name[23];
char num[15];
double sum;
public:
BankAccout(char *nm, char *nr, double s) {
strcpy(name,nm);
strcpy(num, nr);
sum = s;
}
};
int main()
{
BankAccout k("Peter", "0403940940", 34.21);
}
as a coffee break exercise here is more idiomatic version
#include "pch.h"
#include <iostream>
#include <string>
class BankAccount {
std::string name_;
std::string num_;
double sum_;
public:
BankAccount(std::string name, std::string num, double sum) {
name_ = name;
num_ = num;
sum_ = sum;
}
};
int main()
{
BankAccount k("Peter", "0403940940", 34.21);
}
The signature of the constructor does not match.
This one will match:
BankAccount(const char *nm, const char *nr, double s);
EDIT:
The reason is the way you are calling the constructor in the main function. You are giving literal strings as parameters. These literals are const, you cannot change them at runtime. Thus you will pass pointers to const char*.
This is very obvious if you look at this opposing example. This is a way that would be compatible with the old signature BankAccout(char *nm, char *nr, double s);.
int main(int argc, char* argv[])
{
char name[] = "hello";
char number[] = "1234";
std::cout << "name before: " << name << std::endl;
BankAccount k(name, number, 8.5);
// name and number are not const,
// you can change them :
name[2] = 'x';
name[3] = 'x';
std::cout << "name after: " << name << std::endl;
return 0;
}
An even simpler version, if you don’t need to have additional functionality in the class: just use a struct.
#include <string>
struct BankAccount {
std::string name;
std::string number;
double balance;
};
int main() {
BankAccount account{"Joy", "44", 43.};
}

Cannot display file(related to classes)

So I am trying to read in a file using private class variables. I am unsure how to display the file. There might be another way to do this, but this is what I could think of. Note, its my first project using classes and private and public/private members. Was I on the right path atleast? I keep getting an error for the int main function. How can I fix it?
This is my main:
#include "Record.h"
#include <sstream>
int main ()
{
Record employee;
ifstream myFile;
myFile.open("Project 3.dat");
string str;
int i=0;
if (myFile.is_open())
{
while (getline(myFile, str))
{
istringstream ss(str);
ss >> employee.get_name(str) >> employee.get_id(stoi(str)) >>
employee.get_rate(stoi(str)) >> employee.get_hoursWorked(stoi(str));
}
}
return 0;
}
This is my header:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
class Record
{
private:
string name;
int id;
double rate;
double hours;
public:
Record();
Record (string n, int empid, double hourlyRate, double hoursWorked);
// constructor
void read_data_from_file();
double calculate_wage();
void print_data();
/* ASETTERS AND GETTERS */
void set_name (string n);
string get_name();
void set_id (int empid);
int get_id();
void set_rate (double hourlyRate);
double get_rate();
void set_hoursWorked(double hoursWorked);
double get_hoursWorked();
/* END OF SETTERS AND GETTERS */
};
This is my cpp
#include "Record.h"
Record::Record():name(), id(0), rate(0), hours(0) {} //default constructor
must be implemented first
Record::Record(string n, int empid, double hourlyRate, double hoursWorked)
{
name = n;
empid = id;
hourlyRate = rate;
hoursWorked = hours;
}
//
void Record::set_name(string n)
{
name = n;
}
string Record::get_name()
{
return name;
}
//
void Record::set_id(int empid)
{
id = empid;
}
int Record::get_id()
{
return id;
}
//
void Record::set_rate(double hourlyRate)
{
rate = hourlyRate;
}
double Record::get_rate()
{
return rate;
}
//
void Record::set_hoursWorked(double hoursWorked)
{
hours = hoursWorked;
}
double Record::get_hoursWorked()
{
return hours;
}
//
double Record::calculate_wage()
{
return (rate * hours);
}
There are some issues with your code that I can see. most of your problems aren't related to your question (I mean using a class or private/public members). you have more basic misunderstandings. So here's some explanation that might help you:
1- Using functions : You have some troubles using your defined functions, A function can have multiple input parameters and one return value. basically it's like this return_type function_name(parameter_type param1, ...). it means that if you call this function you need to pass param1,... and expect your function operation and then have a return value of return_type. You defined some set and get functions. if you want to set something you should call set function and pass your desired value to it and it will copy your value to your defined member data, after that you can call get function to retrieve that value. So when you call get function with parameter it will raise error. Here you want to call set function.
2- Using stoi : As you can see you are getting error on using stoi function too, this is a function for converting string to integer, The thing that you missed here is that this function declared in std namespace. If you want to use it you need to use it like this std::stoi(str). one other thing, using namespace std is a bad practice.
3- Design matters : In OOP design, a class must have a purpose and an actual job to do. It might be an interface to abstract class but a bunch of set and get functions will not fulfill the need to create a class. Here if your class is going to do file operations, it's OK, but as far as you shared your code it's just some set and get functions.

Error with Class in C++ for my project

I am new to this. Basically I just learnt how to use class in C++. When I try to print out, the values just seem to be 0. Can anyone help me out? Its supposed to print out:
Susan Myers 47899 Accounting Vice President
Mark Jones 39119 IT Position
Joy Rogers 81774 Manufacturing Engineer
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;
class Employee
{
private:
string name;
int idNumber;
string department;
string position;
public:
Employee()
{
name=" ";
idNumber=0;
department=" ";
position=" ";
}
Employee(string, int, string, string)
{
int id;
string n,d,p;
name=n;
idNumber=id;
department=d;
position=p;
}
Employee(string, int)
{
string n;
int id;
name=n;
idNumber=id;
}
void setName(string)
{
string n;
name=n;
}
void setId(int)
{
int id;
idNumber=id;
}
void setDepartment(string)
{
string d;
department=d;
}
void setPosition(string)
{
string p;
position=p;
}
string getName() const
{
return name;
}
int getId() const
{
return idNumber;
}
string getDepartment() const
{
return department;
}
string getPosition() const
{
return position;
}
};
int main()
{
Employee e1;
Employee e2;
Employee e3;
e1.setName("Susan Meyers");
e2.setName("Mark Jones");
e3.setName("Joy Rogers");
e1.setId(47899);
e2.setId(39119);
e3.setId(81744);
e1.setDepartment("Accounting");
e2.setDepartment("IT");
e3.setDepartment("Manufacturing");
e1.setPosition("Vice President");
e2.setPosition("Programmer");
e3.setPosition("Engineer");
cout<<"---------------------------------------"<<endl;
cout<<"Name"<<setw(6)<<"ID Number"<<setw(10)<<"Department"<<setw(12)<<"Position"<<endl;
cout<<e1.getName()<<setw(6)<<e1.getId()<<setw(10)<<e1.getDepartment()<<setw(12)<<e1.getDepartment()<<endl;
cout<<e2.getName()<<setw(6)<<e2.getId()<<setw(10)<<e2.getDepartment()<<setw(12)<<e2.getDepartment()<<endl;
cout<<e3.getName()<<setw(6)<<e3.getId()<<setw(10)<<e3.getDepartment()<<setw(12)<<e3.getDepartment()<<endl;
return 0;
}
This is what you get when you rely on guesswork rather than properly reading an introductory textbook on C++
A constructor of the Employee class which (apart from a blank line that I've removed) you define as
Employee(string, int, string, string)
{
int id;
string n,d,p;
name=n;
idNumber=id;
department=d;
position=p;
}
has the following effects.
The four arguments passed by the caller are ignored, since they are not named.
Four default-initialised variables (id, n, d, and p) are defined local to the constructor body. id will be uninitialised. The others, since they are std::string, are default-initialised (to an empty string)
The next four statements copy those variables into class members. The result is that initialising idNumber has undefined behaviour (since id is uninitialised) and the three strings are initialised to empty strings.
To get the effect that (I assume) you intend, change this to;
Employee(std::string n, int id, std::string d, std::string p)
{
name=n;
idNumber=id;
department=d;
position=p;
}
Note that I'm calling string by its full name std::string. That allows removing the using namespace std which (among other things) is BAD practice in header files.
Even better, change this to
Employee(const std::string &n, int id, const std::string &d, const std::string &p) :
name(n), idNumber(id), department(d), position(p)
{
}
which passes the strings by const reference (avoids additional copies of std::strings) and uses an initialiser list instead of assigning to members in the constructor.
Similar comments apply to ALL of the member functions of Employee, except that only constructors can have initialiser lists.
Errors made
Presentation
Your code is extremely cluttered, and has much irrelevant stuff.
Syntax
void setPosition(string){
Here your function has no argument! What is string?
Code
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;
class Employee{
public:
string name;
int idNumber;
string department;
string position;
void setName(string n){
name=n;
}
void setId(int k){
int id;
idNumber=id;
}
void setDepartment(string d){
department=d;
}
void setPosition(string p){
position=p;
}
string getName(){
return name;
}
int getId(){
return idNumber;
}
string getDepartment(){
return department;
}
string getPosition(){
return position;
}
};
int main(){
Employee e1;
Employee e2;
Employee e3;
e1.setName("Susan Meyers");
e2.setName("Mark Jones");
e3.setName("Joy Rogers");
e1.setId(47899);
e2.setId(39119);
e3.setId(81744);
e1.setDepartment("Accounting");
e2.setDepartment("IT");
e3.setDepartment("Manufacturing");
e1.setPosition("Vice President");
e2.setPosition("Programmer");
e3.setPosition("Engineer");
cout<<"---------------------------------------"<<endl;
cout<<"Name"<<" "<<"ID Number"<<" "<<"Department"<<" "<<"Position"<<endl;
cout<<e1.getName()<<" "<<e1.getId()<<" "<<e1.getDepartment()<<" "<<e1.getPosition()<<endl;
cout<<e2.getName()<<" "<<e2.getId()<<" "<<e2.getDepartment()<<" "<<e2.getPosition()<<endl;
cout<<e3.getName()<<" "<<e3.getId()<<" "<<e3.getDepartment()<<" "<<e3.getPosition()<<endl;
}
Output
---------------------------------------
Name ID Number Department Position
Susan Meyers 32767 Accounting Vice President
Mark Jones 32767 IT Programmer
Joy Rogers 32767 Manufacturing Engineer
Explanation
I have shortened your code by 50%(shows how much redundant stuff you had), and here is a working code.
void setDepartment(string d){
department=d;
}
Here, string d is defined IN the function as an argument. Note that your code also cout<< department twice, and I have corrected that for you in my above code.
Hope this helps.