I want to start learning C and download Eclipse for C\C++ and want to start new project.
I found this tutorial and after create new project, choose C project with MinGcc and hit finish this is the errors i got:
Symbol 'EXIT_SUCCESS' could not be resolved
What i am doing wrong ?
EXIT_SUCCESS is defined in stdlib.h:
#include <stdlib.h>
int main(void)
{
return EXIT_SUCCESS;
}
Based on your comments, your problem appears to be with Eclipse. You might want to try off the main menu:
Project->C/C++ Index->
Freshen All Files
Update with Modified Files
Re-resolve Unresolved Includes
Search for Unresolved Includes
In the Project Exlorer tree, it lists where Eclipse CDT looks for include files. You should see a directory in there that holds stdlib.h. On my machine it is in c:\MinGW\include.
Related
I am just starting out with Segger Embedded Studio. Right now trying to call a function of a included header file. The file seems to be included since it shows up in the dependencies. For now I simply included the header and C-File in the project directory.
The included Header- and C-Files are simply:
//##### Header-File ######
#ifndef TEST_H_
#define TEST_H_
void printText(void);
#endif //TEST_H_
and:
//###### C-File #########
#include <test.h>
#include <stdio.h>
#include <stdlib.h>
void printText(void)
{
printf("Hello");
}
But when I try to call the printText Function in my main I get the error:
"Undefined Symbol: printText".
Why is the function not recognized?
"Undefined symbol" is a linker error. You are not linking the object code containing the definition of printText().
It is not an issue with the header file; including a header file does not cause the associated code to be linked - that is just the declaration so the compiler knows what the interface looks like. It is the linker than combines the separately compiled object code to form a program. You have not told the linker to use the object code containing printText(), and you have not told your IDE project to compile it to generate that object code.
The project tree clearly shows that only main.c is included in your project; you need to add the C file containing printText() too.
The concept of separate compilation and linking is what you need to grasp here.
Thank you Clifford for your answer. You are right I had some miss-conceptions about which files will be linked while building the project. In the special case of segger embedded studio there are, as I know by now, two ways to reference extern files.
Adding the files to the sources files folder is straight forward, but must be done separately for each project you want to use the respective files.
For frequently used files it is beneficial to create a dedicated library solution. Such a library can then be imported to any solution by choosing "add existing project". This will add all files of the library to your current solution (and show them in the project-tree). Now click the tab project -> dependencies. Your library should show up here. By acitivating the check box the linker will compile the referenced project upon builing your solution, allowing for the usage of your library functions.
Adding and linking library-project to a current solution
I'm learning C, and I want to use my first external library.
Firstly I'll show the simplistic code I'm trying to compile:
#include <stdlib.h>
#include <iup.h>
int main(int argc, char **argv)
{
IupOpen(&argc, &argv);
IupMessage("Hello World 1", "Hello world from IUP.");
IupClose();
return EXIT_SUCCESS;
}
The external library being IUP.
I have downloaded the following to my documents folder:
Then I configured Netbeans build options by first adding the header file directory:
Then finally I added the .dll file:
https://prnt.sc/slf1z8
(I added a link because I thought the post was getting too long)
However, while the code no longer shows a red underline under the functions I'm trying to use, the compiler shows "cannot find -liup"
I don't know what could be going wrong. I was following this link tutorial:
http://webserver2.tecgraf.puc-rio.br/iup/en/ide_guide/netbeans.html
Thank you!
When you link, even using a DLL, you need a ".lib" or ".a" file depending on the compiler. In this case this library is called an import library, and contains just "pointers" to the functions in the DLL.
The IUP packages include those import libraries you need. Probably you downloaded package iup-3.29_Win64_dllw6_lib.zip which include the ".a" files you will need.
So I have spent the whole day trying to figure this out, and alas I have failed. I need help! So I installed Eclipse and MinGW so that I can write a C program. I am new to all of this. I need to be able to access an sqlite database. So I downloaded the sqlite amalgamation and unzipped it to C:/sqlite3 and it contains two .c files and two .h files. In the examples, I have seen online they include the sqlite.h header file as follows:
#include <sqlite.h>
So I think that I need to add an includes folder holding my sqlite info. So I click on my project and select Properties>C/C++ General>Paths and Symbols. With the "Includes" tab selected and the Language GNU C highlighted, I add the Include directory C:\sqlite3. So far no problems, I can build a project that prints my name in the console.
Now I add some sample code from a tutorial site:
#include <stdio.h>
#include <sqlite3.h>
int main(int argc, char* argv[])
{
sqlite3 *db;
int rc;
rc = sqlite3_open("test.db", &db);
if( rc ){
fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
return(0);
}else{
fprintf(stderr, "Opened database successfully\n");
}
sqlite3_close(db);
}
I get 3 errors claiming undefined reference to the sqlite3 functions. So I think I need to add a link to sqlite3 in the compiler. So now I go to Properties>C/C++ Build/Settings and add -lsqlite3 to the MinGW C Linker Command line. Now my errors disappear when I build the project, but I get a compile error that says this:
c:/mingw/bin/../lib/gcc/x86_64-w64-mingw32/6.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lsqlite3
It looks like it is looking for the sqlite3 files in the MinGW directories. I am stuck. I have tried pasting the file in the MinGW directory and even that doesn't work. I know that I am missing something obvious to the world, but I only have about 5 pieces of hair left on my head and could really use some insight. Please help me to get Eclipse set up using MinGW and accessing Sqlite. Thanks!
The amalgamation is supposed to be compiled together with your other source files. Just add the .c file to your project, as if it were one of your own source files.
I use the Eclipse Luna IDE for C/C++ (CDT) and MinGW for programming C with Microsoft Windows 7.
I try to write a simple program which uses KissFFT
This is not directly a library, this are only some *.c and *.h-Files.
My example program is stored at E:\Programming\Programs\Simple_FFT\
That is my example program:
#include <stdio.h>
#include <stdlib.h>
#include <tools/kiss_fftr.h>
int nfft = 1024;
int inverse_fft = 0;
int main(void) {
kiss_fftr_cfg cfg = kiss_fftr_alloc(nfft, inverse_fft, NULL, NULL);
kiss_fft_scalar timedata[nfft]; //input
kiss_fft_cpx freqdata[nfft]; //output
while (1)
{
timedata[nfft] = 0;
kiss_fftr(cfg, timedata, freqdata);
free(cfg);
}
return 0;
}
As you can see I included kiss_fftr.h.
This file on the other hand is including kiss_fft.h.
In Eclipse, I went to Properties -> C/C++ General -> Paths and Symbols -> Includes -> GNU C -> and there i added the directorys E:\Programming\Libraries\kiss_fft130 and E:\Programming\Libraries\kiss_fft130\tools
Because this are the folders where the needed header files and c files are stored.
So everything fine, not?
But now the curious thing: I can't compile the program with Eclipse. I'm relatively new to programming but as far as I know, if I include a header file and the directory is included in Eclipse, the related *.c-file should be linked automatically.
Instead I get undefinded references:
src\Simple_FFT.o:Simple_FFT.c:(.text.startup+0x3b): undefined reference to `kiss_fftr_alloc'
src\Simple_FFT.o:Simple_FFT.c:(.text.startup+0x86): undefined reference to `kiss_fftr'
c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: src\Simple_FFT.o: bad reloc address 0x20 in section `.eh_frame'
c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: final link failed: Invalid operation
The problem is, that Eclipse is not linking the c-files of KissFFT to the included headers.
So I found two solutions to bypass this problem:
First: Compile the program manually:
gcc -o E:\Programming\Programs\Simple_FFT\Release\Simple_FFT -I"E:\Programming\Libraries\kiss_fft130" -I"E:\Programming\Libraries\kiss_fft130\tools" E:\Programming\Programs\Simple_FFT\src\Simple_FFT.c E:\Programming\Libraries\kiss_fft130\tools\kiss_fftr.c E:\Programming\Libraries\kiss_fft130\kiss_fft.c
As you can see, I included the *.c-Files "kiss_fftr and kiss_fft" manually and compilation is fine.
Second solution: In Eclipse, I went to Project -> Properties -> C/C++ Build -> Settings -> Tool Settings -> MinGW C Linker -> Miscellaneous -> Other Objects -> and added E:\Programming\Libraries\kiss_fft130\kiss_fftr.c and E:\Programming\Libraries\kiss_fft130\kiss_fft.c.
Then the program is compiling fine, too.
Both is not my intention. Because I would have to manually link every *.c-file I use in my program. What is my failure in the properties of Eclipse, that it does not automatically link the correct files together?
Would be very happy to get an answer so I can start programming correctly :)
You need to add your C files folders to the Source Locations in the Project Properties->C/C++ General->Paths and Symbols. Or, if you have your kiss library compiled (.lib or .a) you should add it in the linker section Library Search path and Libraries
I'm stuck with a problem.
Well, I want to create my own dylib file, and inside of it write some methods, etc. You know, just a normal library.
Ok, so I opened Xcode, New project, and I selected Dynamic library. I've created a *main_lib.c* file, and wrote this method inside of it:
void printMessage(char *str){
printf("%s", str);
}
Obviously, I linked this file with the .dylib file and builded the project, no errors. After this, I created another project, selected Command Line Application and created a main.c file.
I imported the builded .dylib file in this project.
I asked one friend of mine, he said that at this point I should create an header file and write inside of it the function prototype of the dylib. So I created a main_lib.h file and declared this prototype:
void printMessage(char *str);
At this point, I write in the main.c file this code:
#include <stdio.h>
#include "main_lib.h"
int main(void){
printMessage("just a try");
return 0;
}
But when I build this it says:
ld: symbol(s) not found for architecture x86_64
It means that the compiler cannot find printMessage, right? But why? What am I doing wrong? Please help :) Thanks in advance guys!
To include it just add it to Target Dependencies and Link With Libraries in "Build Phases" and thats it, it should work.