I don't know why I can't access the function clearConsole() from my .cpp file from the header files, I guess I'm calling it wrong? How do I target the main file from a header file? I try to call the clearConsole() function after the user input in the addCustomer() functinon in customer.h.
Main.cpp
// OTS.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
#include "customer.h"
// Clear function specific to Windows
// Cross platform alternatives are more convoluted to reach desired effect, so have not been included
void clearConsole()
{
#ifdef _WIN32
system("cls");
#endif
}
Customer.h
//customer.H
//The object class customer
class customer
{
//...
clearConsole();
}
If your files are linked together, a forward declaration of the functions should be enough.
Customer.h
//customer.H
//The object class customer
void clearConsole(); // <--- declare function
class customer
{
//....
};
But this structure looks wrong. I would declare the function in a different header, inside a namespace, and define it in a corresponding implementation file:
clearconsole.h
namespace ConsoleUtils
{
void clearConsole();
}
clearconsole.cpp
namespace ConsoleUtils
{
void clearConsole()
{
}
}
Move your clearConsole() method to the header file (I think is not under discussion the implementation under .header files that I actually disagree, but anyway...), and change the system message to the specific one you need, as follows:
#ifndef _WIN32
#include <syscall.h>
#endif
void clearConsole(){
#ifdef _WIN32
system("cls");
#else
system("clear");
#endif
}
I also had this problem in my kernel that I'm writing in C,C++, and Assembly. I was able to fix this problem by telling the ld command to allow shared variables and functions using the -shared flag. In gcc you would just do the same thing because gcc is a linker, assembly, c compiler and a c++ compiler.
Related
I am a complete c++ noob. Start to learn it from the java. So, after hard study with some tutorials, I ended up with this class named Token:
#include "Token.h"
#include <iostream>
using namespace std;
//int Token::frequency = 0;
Token::Token() {
// TODO Auto-generated constructor stub
frequency=0;
tok = "hey i am created";
cout << tok << endl; // prints !!!Hello World!!!
}
Token::~Token() {
// TODO Auto-generated destructor stub
}
The header for this class is this:
#ifndef TOKEN_H_
#define TOKEN_H_
#include <string>
class Token {
std::string tok;
int frequency;
public:
Token();
virtual ~Token();
};
#endif /* TOKEN_H_ */
It looks like in the tutorial, all right. The error is when I called it in my main class:
#ifndef TOKEN_H_
#define TOKEN_H_
#include <iostream>
using namespace std;
int main() {
Token myToken;
cout << "!!!Hello World!!!" << endl; // prints !!!Hello World!!!
return 0;
}
#endif /* TOKEN_H_ */
The error says :
Tokenizer.cpp:15:8: error: expected ‘;’ before ‘myToken’
Whyyy? I looked up the tutorials and answers here, it looks like I am doing it right? What is going on? And, if you see that I did some other crap, pls tell me, I will be thankful, I just came from Java to C++...
You have #ifndef TOKEN_H_ around your main function, which makes no sense. That #ifndef is called a header guard, and it's used to protected headers from being included multiple times. Your main function should go into a source file (.c or .cpp or the like). You do not need header guards in source files since they aren't included from other source files.
You need your main.cpp file to be like this:
#include <iostream>
#include "token.h"
// other stuff, like the using namespace
int main() { /* then your main function. */ }
Actually, most of your source files will follow this sort of pattern. This is the same pattern your Token.cpp file is built with.
You need to include the actual header for your class
#include "Token.h"
That way the class definition is available and you can declare an instance of Token in main
These are header/include guards, you don't need them in your main file
#ifndef TOKEN_H_
#define TOKEN_H_
You are not incluiding the token header #include "token.h", thus, the compiler think that Token myToken; is a definition not a declaration, also you don't need the header guards
remove the #ifndef guards from the main.c file. Also include the Token.h header in main.
I've been teaching myself some OpenGL using SFML for creating windows/handling inputs, etc. My main.cpp started getting a bit unwieldy so I decided to start splitting my code up. I created a 4X_vertex.h and a 4X_vertex.cpp (4X is the name of the project) and moved the relevant functions and structs out of my main and into these files. However, when I compile, I get the error
variable or field "drawVertexArray" declared void
which from my research seems to be just an unhelpful message relating to the next error, which is
vertex was not declared in this scope
Here's my list of includes from my main.cpp:
#include <iostream>
#include <fstream>
#include <string>
#include <SFML/System.hpp>
#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include "4x_vertex.h"
#include "4x_constants.h"
My 4X_vertex.h:
#ifndef _4X_VERT_H
#define _4X_VERT_H
struct vertex{
GLfloat x,y,z;
GLfloat r,g,b;
};
void drawVertexArray(vertex v[]);
vertex* loadVertexData();
#include "4X_vertex.cpp"
#endif
The part of 4X_vertex.cpp that's giving me the trouble:
using namespace std;
void drawVertexArray(vertex v[]){
... openGL stuff...
}
All of this worked before I started moving it around so I'm assuming there's something weird going on with the includes, or something. All help is greatly appreciated!
Just some pointers. Best practice is to divide your project up into multiple source files. Typically, you would use the word "main" in the file name of the main source file (if applicable). So you might have something like...
main.cpp
feature1.cpp
feature2.cpp
tools.cpp
For your other files, you will typically name them after the class they implement. You will most often have both a .h and a .cpp. Put your declarations in the .h and your definitions in the .cpp had have the .cpp include the .h. That might give you...
main.cpp
feature1.cpp feature1.h
feature2.cpp feature2.h
tools.cpp tools.h
The modules that reference one of your classes includes it's .h as well. So, main.cpp might look like...
#include <iostream>
#include "feature1.h"
#include "feature2.h"
using namespace std;
void main(int argc, char **argv)
{ ...
cout << "Done!\n";
}
And feature1.cpp might be...
#include "feature1.h"
#include "tools.h"
feature1_class::feature1_class() { ... }
void feature1_class::AUsefulFeature(int val) { ... }
//etc.
...where feature1.h declares the class, defined constants, etc. f.g.,
#ifndef FEATURE1
#define FEATURE1
#include "tools.h"
class feature1_class
{
public:
feature1_class();
void AUsefulFeature(int val);
int APublicMember;
};
#endif
You may have noticed that tools.h is actually include twice in feature1.cpp. It is included from within the feature1.h and explicitly from the .cpp file. If you use the following pattern in your .h files ...
#ifndef TOOLS_H
#define TOOLS_H
//... do your thing
#endif
... then multiple includes shouldn't cause you any problems. And as you refactor code, it is one less thing to have to worry about cleaning up.
If you have been using a single file for all your source up till now, you may have been compiling like so...
cl main.cpp
Which gives you your .exe and .obj and maybe other files. But with multiple source files involved, it isnt much different. You can say...
cl main.cpp feature1.cpp feature2.cpp tools.cpp
There is much more to learn, but this is a start and helps you on the way to better organization of your coding thoughts.
You need to #include "4X_vertex.h" at the top of your 4X_vertex.cpp file. This will allow the .cpp file to see the declaration for the struct vertex.
In general, each file (both .h and .cpp files) needs to #include any header files which contain declarations for items used in that file. This includes the standard headers and OpenGL headers, as well as your custom ones.
#ifndef _MY_OPENCLPLATFORM_
#define _MY_OPENCLPLATFORM_
#include "OpenCL.h"
namespace my
{
class OpenCLPlatform
{
cl_platform_id mplatformID;
cl_uint mnumDevices;
std::vector<OpenCLDevice> mdevices; // OpenCLDevice was not declared in this scope
public:
OpenCLPlatform(cl_platform_id platformID);
void getDevices();
void printInfo();
cl_platform_id& getPlatformID();
};
}
#endif
#ifndef _MY_OPENCLDEVICE_
#define _MY_OPENCLDEVICE_
#include "OpenCL.h"
namespace my
{
class OpenCLDevice
{
cl_device_id mdeviceID;
public:
OpenCLDevice(cl_device_id device);
void printInfo();
void printDeviceType(cl_device_type deviceType);
};
}
#endif
#ifndef _MY_OPENCL_
#define _MY_OPENCL_
#if defined(__APPLE__) || defined(MACOSX)
#include <OpenCL/opencl.h> // This works only for XCODE compiler
#else
#include <CL/cl.h>
#endif
#include <cassert>
#include <iostream>
#include <vector>
#include "Exception.h"
#include "OpenCLDevice.h"
#include "OpenCLPlatform.h"
namespace my {
class OpenCLDevice;
class OpenCLPlatform;
class OpenCL;
class OpenCL
{
cl_uint mnumPlatforms;
std::vector<OpenCLPlatform> mplatforms;
void getPlatforms();
public:
OpenCL();
~OpenCL();
void quickSetup();
void printPlatformVersions();
};
}
#endif
Does the the ordering "class OpenCLDevice; class OpenCLPlatform; class OpenCL;" matter? Sometimes, header files depend on each other which can lead to "hard to follow" or convoluted inclusions...Do you have a "one way" technique to deal with convoluted inclusions that you use all the time?
Edit:
I changed the code to match my real problem. If you look at the code above, the compiler is saying that 'OpenCLDevice was not declared in this scope'.
Edit:
I finally got the code to work, and this is what I did:
1. add #include "OpenCLDevice.h"in OpenCLPlatform.h
2. compile
3. remove #include "OpenCLDevice.h"in OpenCLPlatform.h
4. compile
It works now!
Edit:
I cleaned the project and removed all dependencies, and I'm getting the same errors again.
Edit:
I think compiler did something to the code. It may have chose to not include libraries that aren't used in the header and source file, but are used in other headers and source codes
Since you are including classa.h and classb.h where both classes are (presumably) defined, you shouldn't even need the forward declaration.
However, if you did not include them, then no, order of the declarations wouldn't matter. As long as as a class is forward declared before it is used you should be OK.
I see two potential issues:
Your #include "OpenCL.h" may not include the file you expect (yours), but instead some system file.
Forward declarations can't be used in your case. It works only when you have pointers or references to class instances. Your vector<OpenCLPlatform> requires the class declaration (i.e. inclusion of the corresponding header).
Currently I am working on a c framework and I want to embed a c++ package into it. However, there are lots of naming conflicts occurs. So I decided to to add a namespace to the C++ source. Now the question is should I move the #include "header.h" within namespace { } block? I just spent some time to figure out a bug which was resulted from the following codes.
Original C++ source
In a.h
#include <unistd.h>
struct File
{
void func(int fd);
};
In a.cpp
#include "a.h"
void File::func(int fd)
{
::close( fd );
}
And I added the namespace like this
New a.h
namespace MyAddedNameSpace
{
#include <unistd.h>
struct File
{
void func(int fd);
};
}
New a.cpp
#include "a.h"
namespace MyAddedNameSpace
{
void File::func(int fd)
{
::close( fd );
}
}
And compiler complains that ::close() has not been declared.
The reason Why I put the #include directive inside namespace block is because the c++ package I imported also use #ifndef flag to include header files as follows. So I think the easy way is to put all codes within namespace block {}
#ifndef
#include <header1.h>
#include <header2.h>
...
#else
#include <header3.h>
#include <header4.h>
...
#endif
Now I solved this problem by adding the extra line in cpp file
#include <unistd.h> //new added line
#include "a.h"
namespace MyNameSpace
{
void File::func(int fd)
{
::close( fd );
}
}
But I am not satisfied with this solution since unistd.h header has already been included in a.h, but inside the namespace MyAddedNameSpace, or should I added the prefix MyNameSpace to all the function calls where the compiler complain no such function declared ?
Thanks for the reply.
You SHOULD NOT place #include directives inside your own namespace. What you have done is to place all of the contents of unistd.h inside your namespace as well; thus what used to be (and should remain!) ::close() is now declared as MyAddedNameSpace::close(). This is NOT what you want.
Your "solution" of adding the line #include <unistd.h> at the top of your .cpp file fixes the problem, but only for this one .cpp file. What you've done is included the library header the correct way (without your namespace), and then when your header (a.h) is included, it does #include <unistd.h> again (this time within your namespace), but this time the include guards in that file prevent it from being processed again. So for this .cpp file you're OK, but any other file that does #include <a.h> will have the same problem that you originally had.
There may be some rare occasion where you have a good reason for using #include within your own namespace, but you will most likely be including one of your own headers (or some other file) - NOT a library header! - and even then, it's probably not the ideal solution.
In a.h
#include <unistd.h>
namespace MyAddedNameSpace {
struct File
{
void func(int fd);
};
}
In a.cpp
#include "a.h"
namespace MyAddedNameSpace {
void File::func(int fd)
{
::close( fd );
}
}
Usually it is enough to place the directive using namespace in the .cpp file.
Like that:
using namespace MyAddedNameSpace;
void File::func(int fd)
{
close( fd );
}
Hope it helps..
After fixing the previous problem (see my one other question that I have asked). I had declared more classes.
One of these is called CombatAdmin which does various things: (Header file)
#ifndef COMBATADMIN_H
#define COMBATADMIN_H
#include <string> // Need this line or it complains
#include <Player.h>
#include <Sound.h>
#include <Enemy.h>
#include <Narrator.h>
using namespace std;
class Enemy;
class Player;
class CombatAdmin // Code yet to be commented here, will come soon.
{
public:
CombatAdmin();
void healthSet(double newHealth, string playerName);
void comAdSay(string sayWhat);
void playerFindsChest(Player *player,Weapon *weapon,Armour *armour);
void youStoleOurStuffEncounter(Player *player);
void comAdWarning(string enemyName);
void comAdAtkNote(string attack, double damage,string target,string aggresor);
void entDefeated(string entName);
void comAdStateEntHp(string ent, double hp);
void comAdStateScanResults(string enemyName, double enemyHealth);
string doubleToString(double number);
string intToString(int number);
bool isRandEncounter();
void randomEncounter(Player *player,Sound *sound,Narrator *narrator);
bool combatRound(Player *player, Enemy *enemy, Sound *sound, bool ran);
void playerFindsItem(string playerName,string itemName,double itemWeight,double playerWeight);
void playerFindsGold(string playerName,double coinCnt,double playerCoinCnt);
};
#endif // COMBATADMIN_H
It is then instanced in the main.cpp file like this: (Snippet of the main.cpp file)
#include <iostream> // Required for input and output
#include <Item.h> // Item header file.
#include <Weapon.h> // Header files that I have made for my classes are needed for this program
#include <sstream> // Needed for proper type conversion functions
#include <windows.h> // for PlaySound() and other functions like sleep.
#include <time.h> // Needed to seed the rand() function.
#include <mmsystem.h> // Not sure about this one, possibly defunct in this program.
#include <stdio.h> // Needed for a similar kind of output as iostream for various functions error msgs.
#include <irrKlang.h> // The header file of the sound lib I am using in this program.
#include <Narrator.h> // The narrators's header file.
#include <Pibot.h> // Other header files of classes.
#include <Armour.h>
#include <Player.h>
#include <Weapon.h>
#include <CombatAdmin.h>
using namespace irrklang;
using namespace std;
// Forward referenced functions
void seedRandom(); // Seeds the random number so it will be random as apposed to pseudo random.
string getPlayerName(string temp); // Gets the player's new name.
int main(int argc, char* argv[])
{
// Variables and object pointers declared here.
CombatAdmin *comAd = new CombatAdmin(); // Handles combat.
Narrator *narrator = new Narrator(); // The Narrator that says stuff
Pibot *piebot = new Pibot(); // PIbot, the player's trusty companion
string temp; // Temp string for input and output
However, when I try to compile the project, I get the following error:
C:\Documents and Settings\James Moran.HOME-B288D626D8\My Documents\C++ projects\Test Project\main.cpp|59|undefined reference to `CombatAdmin::CombatAdmin()'|
I am using the Code::Blocks IDE (ver 10.05), with the GNU GCC compiler. The project is of type "Console application". I am using windows XP 32 bit SP3.
I have tried changing to search directories to include where the object files are, but no success there.
As can be seen from the code, the narrator and PIbot are instanced just fine. (then used, not shown)
My question is, therefore, what do I need to do to stop these errors occurring? As when I encountered similar "Undefined reference to x" errors before using libraries. I had just forgotten to link to them in Code::Blocks and as soon as I did, they would work.
As this class is of my own making I am not quite sure about this.
Do say if you need more information regarding the code etc.
You have declared the default constructor (CombatAdmin()) and thus prevented the compiler from automatically generating it. Thus, you either need to 1) remove declaration of the default constructor from the class, or 2) provide an implementation.
I had this kind of error and the cause was that the CombatAdmin.cpp file wasn't selected as a Build target file: Prject->Properties->Build targets
Are you sure you've to include your header as:
#include <CombatAdmin.h>
?
I think you need to include your header file as:
#include "CombatAdmin.h"
And same for other headers written by you, like these:
#include "Armour.h"
#include "Player.h"
#include "Weapon.h"
//and similarly other header files written by you!
See this topic:
What is the difference between #include <filename> and #include "filename"?
My solution was just to add a line in the header before the class defenition:
class CombatAdmin;