I'm writing some header files for a project, but for whatever reason, I'm getting the error "Identifier ' ' is undefined. What am I doing wrong? (It won't recognize string or Boolean as correct)
#include <iomanip>
#include <iostream>
#include <string>
class Camper {
private:
string name;
boolean paid;
public:
void setName(string);
void getName() const;
void setPaid(boolean);
void getPaid() const;
void display() const;
};
Booleans are actually typed as bool in c++.Also the reason it wont recognize string is that string is part of the std namespace.You either need to add using namespace std; under your includes,or else you need to adress string as std::string.Some more elements from the std namespace are Vector,List,etc.You can take a look at those here
EDIT:Also I just noticed your getter/setter methods.A getter method is used so you can access Object attributes without them being public,it returns a type of that attribute.If you want to access name described as an std::string your method should return std::string.Meaning your 2 getters should look like this:
bool getPaid() const;
std::string getName() const;
As L.F. pointed out it is not good practice to use namespaces as it can lead to confusing or even conflicting code.The reference is this
Related
This question already has answers here:
When to use const and const reference in function args?
(4 answers)
C++ Const Usage Explanation
(12 answers)
Closed 4 years ago.
I am trying to learn how to use the keyword const while making header and class files (using OOP). Aka learning the correct way to incorporate the keyword 'const' while making and calling the functions.
// Example.h
class Example {
public:
string getName() const;
void setName(const string aName);
private:
const string name;
};
// Example.cpp
#include "Example.h"
#include <string>;
#include <iostream>;
Example::Example();
string Example::getName() const{
return name;
// the following setter does not work
void Example::setName(const string aName){
name = aName;
}
I figured out how to declare variable and getter/setter functions, using const in the header file. Just need help in using const with setter function in class file.
// the following setter does not work
void Example::setName(const string aName){
name = aName;"
Of course it doesn't. You declared name to be const so you cannot assign to it (you can only initialize it). Remove const from name and your setter will work.
Beginner here - but i was uncertain what exactly to search for this (presumably common) question.
I am working on a program where I have a given class (Dictionary). I am supposed to make a concrete class (Word) which implements Dictionary. I should mention that I am not to change anything in Dictionary.
After making a header file for Word, I define everything in word.cpp.
I am unsure if I am doing this correctly, but I make the constructor read from a given file, and store the information in a public member of Word.
(I understand that the vectors should be private, but I made it public to get to the root of this current issue)
dictionary.h
#ifndef __DICTIONARY_H__
#define __DICTIONARY_H__
#include <iostream>
#include <string>
#include <vector>
#include <fstream>
using namespace std;
class Dictionary
{
public:
Dictionary(istream&);
virtual int search(string keyword, size_t prefix_length)=0;
};
#endif /* __DICTIONARY_H__ */
word.h
#ifndef __WORD_H__
#define __WORD_H__
#include "dictionary.h"
class Word : public Dictionary{
public:
vector<string> dictionary_words;
vector<string> source_file_words;
Word(istream &file);
int search(string keyword, size_t prefix_length);
void permutation_search(string keyword, string& prefix, ofstream& fout, int& prefix_length);
};
#endif /* __WORD_H__*/
word.cpp
#include "word.h"
Word(istream& file) : Dictionary(istream& file)
{
string temp;
while (file >> temp)
{
getline(file,temp);
dictionary_words.push_back(temp);
}
}
In word.cpp, on the line "Word::Word(istream& file)", I get this error :' [Error] no matching function for call to 'Dictionary::Dictionary()'.
I've been told this is error is due to "Word's constructor invoking Dictionary's ", but I still don't quite grasp the idea well. I am not trying to use Dictionary's constructor, but Word's.
If anyone has an idea for a solution, I would also appreciate any terms related to what is causing this issue that I could look up - I wasn't even sure how to title the problem.
Your child class should invoke parent constructor, because parent object are constructed before child. So you should write something like:
Word::Word(isteam& file) : Dictionary(file)
{
...
}
Seems its better described here What are the rules for calling the superclass constructor?
I'm currently trying to make a game in C++. In my code I'm trying to nest my variables so that my main doesn't have a lot of includes. My problem right now though is that the value of my variables in my class aren't changing. Stepping through the code it shows it setting the value, but it doesn't work. Anyone know what's going on? Thank you in advance.
This is what I have so far:
Location.h
#ifndef LOCATION_H
#define LOCATION_H
#include <string>
class Location
{
public:
Location(void);
Location(std::string name);
~Location(void);
std::string GetName();
void SetName(std::string value);
private:
std::string m_Name
};
#endif
Location.cpp
#include "Location.h"
Location::Location(void): m_Name("") {}
Location::Location(std::string name): m_Name(name) {}
Location::~Location(void)
{
}
std::string Location::GetName()
{return m_Name;}
void Location::SetName(std::string value){m_Name = value;}
PlayerStats.h
#ifndef PLAYERSTATS_H
#define PLAYERSTATS_H
#include "Location.h"
class PlayerStats
{
public:
PlayerStats(void);
~PlayerStats(void);
Location GetLocation();
void SetLocation(Location location);
private:
Location m_Location;
};
#endif
PlayerStats.cpp
#include "PlayerStats.h"
PlayerStats::PlayerStats(void): m_Location(Location()) {}
PlayerStats::~PlayerStats(void)
{
}
Location PlayerStats::GetLocation(){return m_Location;}
void PlayerStats::SetLocation(Location location){m_Location = location;}
main.cpp
#include <iostream>
#include "PlayerStats.h"
using namespace std;
PlayerStats playerStats = PlayerStats();
int main()
{
playerStats.GetLocation().SetName("Test");
cout<< playerStats.GetLocation().GetName()<<endl;
return 0;
}
Your immediate issue is that
Location GetLocation();
returns a copy of the location, so when you call SetName here:
playerStats.GetLocation().SetName("Test");
You're changing the name of the temporary copy, and the change is lost as soon as the semicolon is hit.
More broadly, this kind of design (nesting classes and nesting includes so that main doesn't have a lot of includes, and using a.b.c() style code to access nested members) isn't great C++ style:
Having a bunch of source files that (transitively) include a bunch of header files means that changing a single header file will trigger recompilations of a bunch of source files. Compile times can be a significant issue in larger C++ projects, so reducing compile times by controlling #include's is important. Read up on "forward declarations" for more information.
Writing code like a.b.c() is considered bad object-oriented design, because it reduces encapsulation: not only does the caller have to know about a's details, it has to know about b's also. Sometimes this is the most expedient way to write code, but it's not something to be blindly done just to reduce #include's. Read up on "Law of Demeter" for more information.
If you want to set the result of playerStats.GetLocation(), you could make GetLocation() pass-by-reference (use ampersand, &, on the return argument). Otherwise you are just setting values in a temporary copy of PlayerStats::m_Location.
Alternatively, you could use the SetLocation() function.
Helo stack people, I need your help in work I make. So I have to .h files first one is Course and the second is Student and I try to create function call getCourses but Unfortunately It's not going so well.My realization "Course ** courses" do not pass compiling and I do not know why not. I would appraise if you can help me to Understand my mistake and help me to fix them thanks.
getCourse - return list of courses
my Course .h file
#ifndef _CORSE_H
#define _CORSE_H
#include <iostream>
#include "Student.h"
class Course
{
public:
void init(std::string getName, int test1, int test2, int exam);
std::string getName();
int* getGrades();
double getFinalGrade();
private:
std::string _name;
int _exam;
int _test1;
int _test2;
};
#endif
My Student .h file-
#ifndef _STUDENT_H
#define _STUDENT_H
#include <iostream>
#include "Course.h"
class Student
{
public:
void init(std::string name, Course** courses, int crsCount);
std::string getName();
void setName(std::string name);
double getAvg();
int getCrsCount();
Course** getCourses();
private:
std::string _name;
Course** courses;
int _crsCount;
};
#endif
My get course function -
Course** student::getCourses()
{
return(this->courses);
}
The problem in the "Course** getCourses();"initialization and this applies also to the init function and Course** getCourses(); function.
error C4430: missing type specifier - int assumed. Note:C++ doe not support default-int
You have a circular dependency - each header tries to include the other, and you end up with one class defined before the other. This gives errors, because you have to declare a type before you can use its name.
Course doesn't depend on Student at all, so just remove the #include from that file.
The definition of Student only uses pointers to Course so it doesn't need the full definition. It only needs to know that the class exists, so you can replace the #include with a declaration:
class Course;
A couple more points:
both headers should include <string> since they use std::string; but not <iostream> since they don't use any I/O streams;
names beginning with an underscore and a capital, like _CORSE_H, are reserved. You should remove the underscores.
you've mis-capitalised Student in the final code snippet.
Besides what Mike Seymour wrote your course function uses lowercase student in
Course** student::getCourses()
Whereas you declared the class with a capital S. Case does matter.
I'm trying to do up a screen scraping assignment. My cpp works, but I don't know how to integrate my unit testing. I tried to do a bool check unit test for the file validity but it's giving me this error:
error: cannot call member function 'bool ScreenScrape::getFile()' without object
screenscrape.cpp:
#include "screenscrape.h"
using namespace std;
int main()
{
ScreenScrape ss;
int choice;
...
...
ss.matchPatternTest();
}
screenscrape.h:
class ScreenScrape
{
public:
ScreenScrape();
void parserTest(int choice);
void matchPatternTest();
void setIndexValue(string data, string IndexName);
void setIndexChange(string data);
void setIndexPercent(string data);
void setIndexDate(string data);
bool getFile();
private:
string IndexName;
string IndexValue;
string IndexChange;
string IndexPercent;
string IndexVID;
string IndexCID;
string IndexPID;
string IndexDate;
};
bool ScreenScrape::getFile()
{
string file1 = "yahoofinance.htm";
char* file2 = new char [file1.size()+1]; // parse file for c string conversion
strcpy(file2, file1.c_str()); // converts to c string
ifstream fin;
fin.open(file2);
if(fin.good())
return true;
else
return false;
}
screenscrapetest.cpp:
#include "screenscrapetest.h"
#include "screenscrape.h"
CPPUNIT_TEST_SUITE_REGISTRATION (ScreenScrapeTest);
void ScreenScrapeTest::fileTest()
{
CPPUNIT_ASSERT(ScreenScrape::getFile()); // test file validity
}
screenscrapetest.h:
#ifndef _SCREENSCRAPETEST_H
#define _SCREENSCRAPETEST_H
#include <cppunit/TestCase.h>
#include <cppunit/extensions/HelperMacros.h>
#include "screenscrape.h"
class ScreenScrapeTest : public CppUnit::TestFixture
{
CPPUNIT_TEST_SUITE (ScreenScrapeTest);
CPPUNIT_TEST (fileTest);
CPPUNIT_TEST_SUITE_END ();
public:
void fileTest();
};
#endif
I tried to declare "ScreenScrape ss;" under screenscrapetest.h, use an object (ss) to call getFile() but it's giving me multiples of this error:
/home/user/NetBeansProjects/Assignment1/screenscrape.h:259: multiple definition of `ScreenScrape::getFile()'
I only want to check for file validity with unit testing. Any help will be appreciated.
Thanks in advance!
Regards,
Wallace
bool ScreenScrape::getFile() is not static, so cannot be called as a static function. You'll need to either (a) declare it as static or (b) create an instance of ScreenScrape and call getFile() from it.
Looking at the code, it's not obvious why this function is a method of the class but perhaps it's still in the early stages of development. It can also be refactored to remove lots of redundant code:
bool ScreenScrape::getFile()
{
std::ifstream fin("yahoofinance.htm");
return fin.good();
}
Don't forget your include guards in screenscrape.h:
#ifndef SCREENSCRAPE_H
#define SCREENSCRAPE_H
// Class declaration here...
#endif//ndef SCREENSCRAPE_H
And consider moving the implementation of getFile to the cpp source file. These two steps will prevent you getting the "multiple declaration" errors.
This will fix your compilation errors, but checking for file validity is not a responsibility of a unit test. Unit tests should not interact with the filesystem.
If you're going to be calling ScreenScrape::getfile()rather than ss.getfile(), then getfile() needs be defined as static. The error you're getting is because non-static methods need to be called on a specific object.
It's difficult to track down the error with your version that defines a ScreenScrape object and then uses that to call getfile(); you obviously haven't included all the relevant code since your screenscrape.h file doesn't have 259 lines, and you also haven't shown the revised code in which you "use an object (ss) to call getFile()".