What is the simplest to use c++ library that graphs functions like matlab and octave do? I have looked over several and have found similar major problems with all of them: i cannot compile an empty program that only has
#include <iostream>
#include "header_to_include.h"
int main(){
return 0;
}
i have found koolplot, some wxwidget stuff, sdl_graph, gnuplot++, and something with Qt. ive looked at some of the ones on the list here, but some are for other languages while others use installers or depended on other programs. When I got files extracted and tried compiling my simple code or given example code from within the download, codeblocks always complains about missing headers or variables or some other things.
i would use gnuplot, except i dont want to create gnuplot files from my cpp files, even if its through a pipe. i want to be able to graph straight from the program.
is there nothing that is simply a handful of files in a zip that can be extracted and used in moments rather than having to figure out which files to include, installing/downloading other major libraries, etc?
edit:
for example, i found http://sdl-grapher.googlecode.com/svn/trunk/ and downloaded the files. i already have sdl, so i copied sdlgraph.h into the includes folder and left a copy in the same directory as example.c. when i compile, i find that for some reason, #include <sdlgraph.h> doesnt work. also the int main() has no arguments despite being a SDL program. after fixing that up, i get undefined reference to 15 different functions that i can clearly see in the sdlgraph.h file such as init_graph and draw_grid
About your errors:
Since you're very new to C++ I'll explain your undefined reference errors.
In C++ you can declare a function like this:
void foo();
However, since it's declared, it doesn't main it's defined. Definitions can exist in C++ source file, libraries but also headers.
Defining the previous example:
void foo() {
std::cout << "void foo() has been called." << std::endl;
}
The error you get means that those functions just aren't defined.
I quess you have to link your application with the SDL libraries.
For more info see:
http://content.gpwiki.org/index.php/SDL:Tutorials:Setup
For more info about dynamic and static linking see:
http://www.learncpp.com/cpp-tutorial/a1-static-and-dynamic-libraries/
Hope it helps!
Related
I am trying to compile TetGen and use the code below to tetrahedralize a .ply file although I am getting these two linker errors:
LNK2005 main already defined in tetgen.obj
LNK1169 one or more multiply defined symbols found
The files that are includes in my project solution are "tetgen.h", "predicates.cxx", and "tetgen.cxx", and the folder path that these three files are in is included in my Project Properties > C/C++ > General > Additional Include Directories. I did the same for the "monkey.ply" file as well.
This is all the code in my main file:
#include "tetgen.h"
int main()
{
tetgenio in, out;
in.firstnumber = 0;
in.load_ply((char *)"monkey.ply");
tetgenbehavior* b = new tetgenbehavior();
tetrahedralize(b, &in, &out);
}
Here are the "tetgen.h", "predicates.cxx", and "tetgen.cxx" files I'm using : https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/libigl/tetgen
I researched these errors and looked around a great amount but can't see why this is occurring. Any help would be greatly appreciated.
LNK2005 main already defined in tetgen.obj
This message tries to tell you that your tetgen library contains the main function. Your "main file" also contains a main function. This is a conflict. You should remove your main function from your code, and read the documentation of the tetgen library on how to provide a replacement. Typically, libraries which define their own main functions require you to rename your main to have some other name, which the documentation should clearly specify.
#include "tetgen.h"
int main_replacement_called_by_tetgen()
{
...
}
For anyone who may have this issue in the future with TetGen: The problem was that the TETGEN_LIBRARY flag needed to be defined in tetgen.h. I knew this, but every time I defined the flag, it would cause memory errors without fail. So, I kept TETGEN_LIBRARY undefined to avoid the memory error. Turns out, with TETGEN_LIBRARY defined, it will work. The problem was that "monkey.ply" did not exist/was in the wrong folder. Because "monkey.ply" did not exist it threw an unhandled exception. Why TetGen does not have a simple handle to check if a file exists before it tries to load it or not is beyond me. But that fixed things.
I have been making some applications that I would like to link to discord, specifically with Discord's SDK. The SDK comes with 64 and 32 bit x84 lib files, and a C++ folder full of the includes it needs, so I would assume C++ is supported.
However, I am very terrible at linking libraries or anything at that, and always run into issues when linking. I am using Dev C++ as my IDE, and my code is as follows:
#include <iostream>
#include "Discord/discord.h"
using namespace std;
void InitDiscord()
{
auto discid = 772671910668133376; //Not my actuall discord app ID, but real one does not make a difference
discord::Core* core{};
discord::Core::Create(discid, DiscordCreateFlags_Default, &core);
}
int main(){
InitDiscord();
cout << "Discord active";
while(1){
}
return 0;
}
and I am getting the error:
C:\TDM-GCC-64\x86_64-w64-mingw32\bin\ld.exe Discord Testing.o:Discord Testing.cpp:(.text+0x32): undefined reference to `discord::Core::Create(long long, unsigned long long, discord::Core**)'
for only the line discord::Core::Create(discid, DiscordCreateFlags_Default, &core); and not discord::Core* core{};
I am using C++17 and a newer TDM-GCC compiler, the same one that works for all of my other applications. I am including the .lib files and .dll files in the program's directory, and in the linker the only thing I am using is -discord_game_sdk.dll.lib which is a valid directory. I have also tried discord_game_sdk.dll.lib and putting the library in the same directory as the includes: Discord/discord_game_sdk.dll.lib. I have tried using both 32 bit and 64 bit libraries in all project and compiler directories with no change, and im sure this is something probably really simple, but nowhere have I found any example C++ discord programs or how to include their SDK.
If anyone could figure out what the problem is and how I can fix it, that would be very helpful and appreciated.
EDIT:
It appears that user4581301 was right, TDM-GCC and other Mingw compilers do not support .lib files, and will ignore them despite being linked. The SDK did not come with any other formats other than .dylib, .so, and .bundle.
This creates a somewhat new issue, I already have my compiler set up and cannot really switch to Visual Studio, so I need a way to convert .lib to .a somehow. A post here recommends http://code.google.com/p/lib2a/ , which requires a .def file, another file that did not come with the SDK, but apparently a program called gendef.exe that came with my compiler can create .def files from .dll files. That is indeed the case, however when attempting it I get the error:
C:\Program Files (x86)\Dev-Cpp\MinGW64\x86_64-w64-mingw32\bin>gendef.exe discord_game_sdk.dll
* [discord_game_sdk.dll] Found PE image
* failed to create discord_game_sdk.def ...
with no other warnings. Now I need to know if I am converting wrong, if there is an easier workaround, or if one of the other file types can be converted or used. Any suggestions at this point are welcome and appreciated!
I am using Eclipse kepler for AVR development.
The code that I have is C (Open Source), and I've gotten it adjusted so it runs perfectly. My target is an ATmega2560, in the form of an arduino mega2560.
Using the arduino board is strictly for hardware convenience; we are developing the hardware to be a custom board with most of the core arduino mega2560 components.
I need to use several libraries with this project that are only available as arduino libraries, namely libraries for an e-paper screen (from seeedstudio) and Nordic's BLE nRF8001.
If I create a new arduino project using the plugin in eclipse, I can build and run the tests for the arduino libraries perfectly.
When I try to merge the 2 code bases together, I can't seem to call the functions in the added arduino libraries - if I call them the compiler throws a linking error.
Building target: Virgin2ManualArdInsert.elf
Invoking: AVR C Linker
avr-gcc -Wl,-Map,Virgin2ManualArdInsert.map -mmcu=atmega2560 -o "Virgin2ManualArdInsert.elf" ./avr/adc.o ./avr/eeprom.o ./avr/lcd_and_input.o ./avr/main.o ./avr/strings.o ./avr/unimplemented.o ./avr/usart.o ./aes.o ./baseconv.o ./bignum256.o ./ecdsa.o ./endian.o ./fft.o ./fix16.o ./hash.o ./hmac_sha512.o ./messages.pb.o ./p2sh_addr_gen.o ./pb_decode.o ./pb_encode.o ./pbkdf2.o ./prandom.o ./ripemd160.o ./sha256.o ./statistics.o ./stream_comm.o ./test_helpers.o ./transaction.o ./wallet.o ./xex.o
./avr/main.o: In function `main':
main.c:(.text.startup.main+0xc): undefined reference to `writeEink'
collect2: error: ld returned 1 exit status
makefile:53: recipe for target 'Virgin2ManualArdInsert.elf' failed
make: *** [Virgin2ManualArdInsert.elf] Error 1
As a test, I'm just trying to call a basic "write to display" call in eInk.cpp from main.c:
extern "C"{
void writeEink()
{
EPAPER.begin(EPD_SIZE); // setup epaper, size
EPAPER.setDirection(DIRNORMAL); // set display direction
eSD.begin(EPD_SIZE);
GT20L16.begin();
// int timer1 = millis();
EPAPER.drawString("testing", 10, 10);
EPAPER.drawNumber(12345, 60, 40);
EPAPER.drawFloat(-1.25, 2, 80, 65);
EPAPER.display(); // use only once
}
Is a static library built from the arduino cores the way to go here? I've tried it (though it seems most of the procedures are outdated) and the libraries do not want to link/be called.
What is the correct procedure for including C++/Arduino calls in my C code?
I've tried using extern "C" {function()}; in my .cpp files and .h files but to no use.
Thank you for any help or pointers to where I can figure it out for myself.
You can try to compile your C code as C++ by simply renaming the files to *.CPP, but chances are that you have to modify your code to make it compile as C++ code. There are things that are allowed for C, but not for C++ (like calling functions that are not declared).
The other solution is to wirte wrappers around the C++ functions that you want to use from C.
You have to consider two limitations of C against C++:
C is not object oriented
C does not support overloading of functions
This example for Serial.print() shows how you can handle this with a wrapper:
extern "C" void SerialPrintInteger( int value )
{
Serial.print( value );
}
In this example you would write similar functions like SerialPrintFloat(), SerialPrintString() etc.
The extern "C" prefix tells the compiler to create the function in a way that makes it callable from C.
The error you received above isn't a compiler error, it's a linker error. I haven't used Eclipse for Arduino development, I just stick with the Arduino IDE, but the standard Arduino projects expect all of your code to be in a single source file, which it compiles and then links with the Arduino libraries. Arduino programs don't have a C/UNIX-style "main" function, the standard functions are "setup" and "loop."
I recommend going back to one of the Arduino example programs, blink for instance, and watching the console log as Eclipse compiles and links the program. What's happening here is:
The C/C++ compiler compiles your source code, including setup(), loop(), and any other functions you have created, into an object file.
The Linker links this single object file with the Arduino runtime, and any Arduino libraries you have specified. The output of this is an image of the program, in your example above it's trying to make 'Virgin2ManualArdInsert.elf'.
The uploader (probably avrdude) loads this image into your Arduino and resets it.
The Arduino comes out of reset and runs your new code.
If your program is reasonably small, say not more than a few hundred lines, just put all the functions in the one source file, then you won't have to learn how to drive the linker.
If you need, for some reason, to have the sources in a separate file (maybe they're shared with another program, or another platform), then you'll have to learn how to get Eclipse to link the object files from your multiple source files. This may just involve adding the sources into your Eclipse project properly, or you may have to write a Makefile or something similar.
As for C vs C++ source code, you can usually drop a C function into a C++ source file and compile it. There are a few differences, but this way you don't need to worry about "C" linkage or any of that silliness.
I built Qt from source (dlls) and am trying to build an application that uses the Qt dlls. I don't have a lot of experience with C++ so I'm running into what I'm sure is a very basic issue.
My builds are failing on the includes with errors like so:
Fatal error: QNetworkProxy: No such file or directory
Here is the g++ command I am using (I also used -L to add the correct folder to the lib path, but that also didn't work):
g++ -l..\..\wkqt\bin\QtCore4.dll -l..\..\wkqt\bin\QtNetwork4.dll -l..\..\wkqt\bin\QtWebKit4.dll -I..\include -Ishared -Ipdf -Ilib -Iimage -o ..\bin\wkhtmltopdf.exe pdf\*.cc lib\*.cc image\*.cc shared\*.cc
I tried in Visual Studio as well (assuming it wouldn't build, but I wanted to see if I could at least include the Qt dlls from there properly) and I am getting the same errors. Am I doing something wrong with the way I am compiling with g++? If I am linking with the Dlls properly then what is the proper way to use Qt functions from my code?
To clarify, I am not looking for how to properly use Qt. My question is: what is the proper way to use functions defined in any Dll from native C++ code? I apologize if this is a very basic question, but I'm unable to find a clear answer on Google and I don't have any experience with C++ and including third party libraries for use from C++ code.
DLLs can be used by dynamicly loading them and calling their used functions.
to call the exposed functions first define their syntax in the begining
suppose function is syntax is
BOOL MyFunction(int a,char* pszString)
then define syntax
#typedef BOOL (WINAPI *PMYFUNCTION)(int a,char* pszString)
then make object
PMYFUNCTION pfnMyFunction;
and get valid pointer by calling GetProcaddress after loadlibrarycall
HMODULE hlib= Loadlibrary("c:\\Mylib.dll");
if(hlib)
{ pfnMyFunction = (PMYFUNCTION)Getprocaddress(hlib,"MyFunction"); }
Hope this helps...
I'm a novice at C++. Be patient if this is incoherent. I'm called upon to build a large system on linux that was originally built on OS X, where it works fine. The original authors are no longer with the company. The build system makes use of autotools, but there are also some hand made Makefiles which walk through the system calling the auto-made Makefiles. I've managed to get all of the c++ code compiled. The build system also uses libtools, and shared libraries are produced and deposited in /usr/local/lib.
So now I'd like to use these libraries. I've written a short program that simply instantiates an object of class ds_dictionary and calls one of its methods. Here it is:
#include <iostream>
#include <DSUtils/DSUtils.h>
int main (int argc, char * const argv[]) {
int32_t integer_data=123;
char key_alice_integer[] = "alice_integer";
ds_dictionary my_dict;
my_dict.add_int(key_alice_integer, integer_data);
return 0;
}
I compile this with
g++ -lDSUtils -o main my_test_code.cpp
With the result:
//usr/local/lib/libDSUtils.so: undefined reference to `ds_breakdown_from_time_interval'
//usr/local/lib/libDSUtils.so: undefined reference to `ds_date_breakdown_with_string'
//usr/local/lib/libDSUtils.so: undefined reference to `ds_seconds_duration_of_interval'
... (about 25 lines like these)
collect2: ld returned 1 exit status
Let's look inside the library:
garyp#VM:/usr/local/lib$ nm libDSUtils.so | grep ds_breakdown_from_time
U ds_breakdown_from_time_interval
The "U" in the line above ... does that mean that the library wasn't built correctly?
Am I calling g++ correctly?
Do I have to put something in the code to tell it that I'm using functions found in that library?
What are possible errors? Where should I start poking around?
EDIT:
Aha. The library DSUtils is built from several c++ sources. There is one c program in the source, and it contains all of the problem functions. The Makefile system doesn't deal at all with that one c file. That c program compiles. Ideally I suppose I'd figure out how to modify the Makefile to compile that file and add it to the library, but I'm not to the point where I can figure out how to do that.
Can I add the .o file to the existing library? How? Create a library with one file? etc?
EDIT_2: I simply did
g++ -o main -lDSUtils main.o my_new_objectfile.o
and the thing compiles, links, and runs without error. Should that work? After fixing a logic bug, it does work.
This
U ds_breakdown_from_time_interval
tells me that ds_breakdown_from_time_interval will be resolved by another library during runtime. So I am guessing you need to link to the library that defines ds_breakdown_from_time_interval.