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.
Related
I am trying to create a class object s2 with some customized attributes and some attributes from default constructor however my output is the wrong output for the get_year function. It should be outputing 0 which is the key for FRESHMAN but it is out putting 2 instead. The rest of the code is outputting as expected:
#include <stdio.h>
#include <iostream>
#include <algorithm> // for std::find
#include <iterator> // for std::begin, std::end
#include <ctime>
#include <vector>
#include <cctype>
using namespace std;
enum year {FRESHMAN, SOPHOMORE, JUNIOR, SENIOR};
struct name
{
string firstName;
string lastName;
friend std::ostream& operator <<(ostream& os, const name& input)
{
os << input.firstName << ' ' << input.lastName << '\n';
return os;
}
};
class Student: name{
private:
name Name;
year Year;
int idNumber;
string Department;
public:
void setname(string fn="", string ln="")
{
Name.firstName =fn;
Name.lastName =ln;
}
name get_name()
{
return Name;
}
void set_year(year yr=FRESHMAN)
{
Year=yr;
}
year get_year()
{
return Year;
}
void set_ID(int ID=0)
{
idNumber=ID;
}
int get_ID()
{
return idNumber;
}
void set_Department(string Dept="")
{
Department=Dept;
}
string get_Department()
{
return Department;
}
};
int main()
{
Student s2;
s2.setname("Nikolai", "Khabeboolin");
s2.set_ID(12436193);
cout<<"ID is: "<< s2.get_ID()<<", name is "<< s2.get_name()<<", year in school is: "<<s2.get_year()<<", Department is "<<s2.get_Department()<<endl;
return 0;
}
Student lacks a constructor, so all its members are default initialized, and the default initialization of year Year and int idNumber is "no initialization", so reading from them is undefined behavior. Reading them might find 0, 2, a random value each time, or crash.
I see that your class contains a void set_year(year yr=FRESHMAN) member, but your code never called set_year, so no part of this executed.
You should make a default constructor for Student, or as Goswin von Brederlow stated, use year Year{FRESHMAN}; and int idNumber{-1}; when declaring the members, to give them default initializations.
By not explicitly declaring and defining a constructor, in this case Student(), you open yourself up to undefined behavior. Your constructor should call set_year(year yr=FRESHMAN) OR even better, just set the year itself.
I am new to using pointers with c++, so I am trying this small code but the problem is that when i try to print name i get this random weird number \364\277\357\376\326\241+ \310\364\277\357\376\310. This is not the memory address, which is confusing and what confuses me more that when i replace name with getName() it works perfectly and prints the name! Thanks you!!
Person.cpp
#include "Pesron.hpp"
#include <string>
#include <iostream>
using namespace std;
Person:: Person()
{
}
Person::Person(string Name, int Age)
{
name=&Name;
age=Age;
}
void Person:: setName(string Name)
{
name=&Name;
}
void Person:: setAge(int Age)
{
age=Age;
}
string Person:: getName()
{
return *name;
}
int Person:: getAge()
{
return age;
}
void Person:: display()
{
cout<<*name<<" "<<age<<" ";
}
Person::~Person()
{
}
Student.cpp
#include "Student.hpp"
Student:: Student(string Name, int Age,int Grades, int ID):Person(Name , Age)
{
grades=Grades;
id=ID;
}
void Student:: setId(int ID)
{
id=ID;
}
int Student:: getId()
{
return id;
}
void Student:: setGrades(int Grades )
{
grades= Grades;
}
int Student:: getGrades()
{
return grades;
}
void Student:: display()
{
Person::display();
cout<<grades<<" "<<id<<endl;
}
main.cpp
#include "Pesron.hpp"
#include "Student.hpp"
#include "graduteStudent.hpp"
#include <iostream>
int main(int argc, const char * argv[]) {
// insert code here...
Student student("ZAID",21,2211,11);
student.display();
return 0;
}
Output
\364\277\357\376\326\241+ \310\364\277\357\376\310 21 2211 11
Person::name looks like it is a std::string *. In Person::Person(string Name, int Age) you pass the paramater Name by value and then store the address of this local variable in name. When Name goes out of scope you have a dangling pointer.
(This also applies to void Person::setName(string Name))
Dereferencing Person::name is undefined behaviour, because the object it is pointing doesn't exist anymore. The solution is to simply store a std::string and not just a pointer to it.
So you get something like
class Person {
private:
std::string name;
int age;
public:
Person(std::string Name, int Age) : name(Name), age(Age) {}
};
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;
}
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.
I'm trying to create a member function that allows an user to set member array variables.
I've been looking everywhere but I can't find the problem in my code,
#include <string>
#include <iostream>
using namespace std;
class Employee
{
protected:
string name;
char ssn[11];
char id[5];
char hired[8];
public:
Employee(char ssn, char id, char hired); //Constructor
Employee(string name);
~Employee(); //Destructor
void setName(string n) { n = name; }
void setSSN(char i) { ssn = i; }
};
int main()
{
return 0;
}
Let's have a look at your setSSN function:
void setSSN(char i) { ssn = i; }
SNN, which most likely means social security number, doesn't consist of just one digit but 11, right? Then why would setSSN take as input only one character (digit) by (char i)? So setSSN function should rather take a string of characters containing SSN of the employee and that string should be of the same flavor as the ssn member variable of your Employee class in order to let you assign one string variable by another in the body of setSSN function. If you are already familiar with the string class of the C++ standard library, you should probably use that class for all your string storage and manipulation.