I'm using other's class for generating delaunay triangle. Its class has two files: VoronoiDiagramGenerator.h and VoronoiDiagramGenerator.cpp. It is all encapusulated into a class.
I want to call the class method in my main.cpp file, so I should include the VoronoiDiagramGenerator.h file.
If i want to use gcc or g++, how do I set the cmd parameter? Before I just used gcc -o main.cpp or something similar.
If I want to use makefile, how would I write it?
If I want to compile the two files (VoronoiDiagramGenerator.h && VoronoiDiagramGenerator.cpp) into a So file, how should I do?
I just test the souce code. When i under windows vc++, add the .cpp and .h into the project workspace, it will be OK. If i just include the .h file in my main file and it give some similar error like linux.
some unreference error.
so i think in my main file just include the out class headfile and gcc main.cpp is error.
In your main.cpp include VoronoiDiagramGenerator.h and use it.
If .h file is not in your current or project directory, make sure to include -Idirectory
Related
For example:
I have a class called A. And there is:
A.hpp
A.cpp
main.cpp
for my project
By default, I only need to include A.hpp in the main so I can compile it, either using IDE such as Xcode or using:
g++ main.cpp A.cpp -o xxxxx
But the submission system only allows me to use:
g++ main.cpp -o xxxx
I tried to include A.cpp in the main, but the IDE says: main file cannot be included recursively when building a preamble
Is there any solution? I want to keep my hpp and cpp separately.
Can I include a cpp file
In theory, any file can be included.
But as a convention, you should never include cpp files.
But the submission system only allows me to use:
g++ main.cpp -o xxxx
If you cannot compile A.cpp then don't write such file at all. Write the definitions that you would have written in A.cpp into main.cpp instead. This achieves the same as including with a macro, but there won't be duplicate definitions in another cpp file.
You can #include any file you want. #include is automatic copy-paste. It looks in the file you tell it to include, and it reads whatever's in the file, and it pretends you wrote that in your original file. It doesn't care what's in the file, it just does that. You can include a .h file, a .hpp file, a .cpp file, a .txt file, a .py file, a .jpg file, or anything you want, as long as it's got valid C++ code in it.
Note that including a .cpp file is not the same as compiling it separately. And people expect that .cpp files are compiled separately, not included. To avoid confusing other programmers or the future version of yourself, you should rename the file to something else if you want to include it. You don't have to, but you should. If it's not a normal header file either (because you can't include it more than once), then you can make up some completely different extension, like .inc.
I'm new to C++, and having difficulty understanding the steps of class object files getting created and compiled.
Let's say I create 3 files: 1. class header file 2. class cpp file (member function definitions present) 3. main cpp file
/*
When I run the main cpp file which includes the class header file (say as "#include class.h"), when does class cpp file get compiled, object file created, and linked?
The reason why I'm having difficulty is that from the compiler point of view, when it sees the main cpp file, there is only the header definition, no member function definition. However, even in the class header file, there is no class cpp file included. How would compiler know to run the class cpp file when it is not referred to in either class header file and the main cpp file?
*/
Let me clarify my question.
// Maybe I've said things I don't even understand lol.
So, basically I'm trying to run a main function in a say 'main.cpp' file. This 'main.cpp' file includes the 'class.h' header (include "class.h"). How would compiler execute the functions defined in header file when member function is not declared in 'class.h?' All my member function declaration is in 'class.cpp,' which is not included in 'class.h' or 'main.cpp.'
I suspect you're using an IDE, since you mention running cpp files - compilers don't know how to run anything.
Your IDE manages these dependencies for you.
When you press "Run", the IDE will decide which files in your project need compiling, and when the compilation is done it will link all the object files together.
If compilation and linking succeeded, the IDE then launches the executable program.
If you want a better understanding of the concepts, step away from your IDE and do all your compilation and linking on the command line for a while.
(It's not complicated, only tedious.)
You need to compile every .cpp file. Headers; .h files, are just for declarations, means that to let the compiler determine if you use the functions correctly. Each .cpp contains code and should be translated to machine code (.o files). After all these compilations, you need to link them to build the executable so that every function used is contained in the same file. The following commands can help you (using g++ compiler):
$ g++ -c myclass.cpp // produces the myclass.o file
$ g++ -c main.cpp // produces the main.o file
$ g++ -o myapp main.o myclass.o // produces the myapp executable
This is oversimplified for the sake of understanding.
I have a makefile that creates object files for two classes (and main) and one of those classes is just defined in a .h file. In my makefile I have a line that says
FileName.o: FileName.h
g++ -c FileName.h
but when I try to compile it says it can't find FileName.o
Do I have to create FileName.cpp in order to get this to compile?
You are using your class from FileName.h somewhere, aren't you? So at least one of your .cpp files should contain #include "FileName.h", and .h's code will be compiled with this .cpp and you needn't compile .h's code separately.
You don't normally attempt to compile a header (.h) file by itself. Including it into an otherwise empty .cpp file will let you compile it and produce a .o file, but it probably won't do much (if any) real good unless you've put things in the header that don't really belong in a header.
I created a class (say, myclass.h/cpp). I want to use the class from many different places. Therefore, I put those files in a folder (say, C:\cpp_include) and I want to include them from whatever folder my codes are. I have a code which uses the class (say, main.cpp). In main.cpp, I include myclass:
#include "myclass.h"
I compile using a .pro file and nmake. In the .pro file, I specify the folder as:
INCLUDEPATH += C:\cpp_include
When I compile the code using nmake, myclass.h is properly included, but myclass.cpp doesn't seem to be found by compiler.
When I specify myclass.cpp as one of the source files in .pro file:
SOURCES += main.cpp C:\cpp_include\myclass.cpp
The exe file is built correctly. But, I would like myclass.cpp file to be found automatically when myclass.h is included, i.e. without setting myclass.cpp as a source file. Would this be possible? It looks like that's what happens with classes from Qt and Qwt (e.g .h/cpp files in /src/ folder in Qt and Qwt). Am I missing somthing?
Thanks a lot!
Daisuke
A simple technique is to have build scripts (makefiles) in the cpp directories. Write a rule that traverses the directories, executing the build scripts. This one step in isolating functionality and also allows one to use libraries.
That's just not how it works. The .cpp is the file that matters, header files (.h) just get copied into the other .cpp files. Therefore you need to add the myclass.cpp to your sources for compiling. Or, if it's a library class, you could also compile it once into a static library (.lib) and just add that to your linker files. But you ultimately need to somehow include you implementation in the project where it's used.
I'm quite new in C++ after few years in Java and eclipse, I got little bit confusing using code::blocks, no autogenerate setter/getter and also implement interface :D.
I wanna ask about code structure in code::blocks, I create new console application, my header will be put to Headers/include folder called Employee.h, then .cpp will be put to src folder.
Now I create main class (I put outside of src folder) who will call the header, I just append the include code like this :
#include "Employee.h"
sure then the errors appeared after compiling:
error : Employee.h: No such file or directory.
how to link the header to the main class properly?
this is my folder structure :
updated :
It works, my include folder needs to be added on build options.
Really thanks
You need to add your include directory to your compiler's include path. This is going to be compiler-specific. e.g., if your structure is:
code
code/src
code/include
and you're running g++ from a terminal in the 'code' directory, you'd need to run (assuming your .cpp is Employee.cpp):
g++ -Iinclude src/Employee.cpp
I suspect you're running some sort of IDE, though: if so, do a search in its help for "include path" and it should tell you how to set it up correctly.
If you want to include your employee.h you must #include "employee.h" not Employee.h. Those are two different files.
You shouldn't be adding include paths to your build options for header files that are actually part of your project. It didn't find the header file from the EmployeeTest.cpp because you didn't use the full relative path.
You need:
#include "include/Employee.h"
You should only be adding include paths to your compiler for additional libraries that aren't added to the typical /usr/local/include or /usr/include directories.