I'm developing something on Minix 3 and, when it comes to deal with io files, I got a problem.
In the code:
#include <stdio.h> /* If I don't call any stdio funcs compiler doesnt's complain*/
int main() {
FILE * fp; /* I get the following: " * not expected " */
return 0;
}
Already tried everything that comes to my mind, can't figure it out..
/EDIT/
From what I can tell, when I include something, if I call functions not related to structs, it's OK. Is it the structs ?
I will assume you have checked whether the Minix file is present, that it really defines the type FILE and that your include path provides the correct -Ioption to the compiler to find that file.
Depending on your environment it could happen that an environment variable INCLUDE exists and is recognized by your compiler to provide additional include paths, recognized even before the include options from the command line. In such a case it might happen to include a stdio.hfrom a different compiler. Visual Studio is known to provide such an environment variable by default, and that has bitten me once before.
EDIT: Running the preprocessor in isolation may help to find out what is really happening in any case. Verify that FILEis defined in the preprocessed version of your file.
Related
I'm having an incredibally hard time finding answers to this for Windows. As if the majority of people use Linux...
Anyways, I need a custom CSV parsing library for C. I found one and downloaded the header file. I tried adding #include <csvparser.h> at the top of my c program but of course, it says file not found. I placed the downloaded file in the same directory as the program.
I think i need to be able to specify an absolute path in the include or place the file csvparser.h in the include directory, but I know how to do neither of these things. What is the default include directory in Windows? I use gcc as my compiler. How can i specify an absolute path in the include statement, on windows? i can find no answer to this.
Thanks!
EDIT
Thank you for the quick reply, I seem to have included the file correctly, but now I'mhaving problems using it.
I found the program at https://sourceforge.net/p/cccsvparser/wiki/Home/
I placed it in the source directory and tried using it, bbut when I try the usage example I'm getting an error. This is my code:
#include <stdio.h>
#include <string.h>
#include "csvparser.h"
#define MAXCHAR 10000
int main() {
// int i = 0;
// file, delimiter, first_line_is_header?
CsvParser *csvparser = CsvParser_new("../MagicProg/Files/MagicProg_csv_ikoria.csv", "|", 1);
return 0;
}
When I try executing this, geany gives me the error:
C:/TDM-GCC-64/bin/../lib/gcc/x86_64-w64-mingw32/9.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:\Users\Geoff\AppData\Local\Temp\ccsiwJPq.o:hello.c:(.text+0x22): undefined reference to `CsvParser_new'
What am I doing wrong? thanks again
If you're including something that's in your source directory you need to use a different style:
#include "csvparser.h"
The angle-brackets form is exclusively for things found in your include path, not in your source directory. That's reserved for things like OS and compiler headers, as well as system-installed libraries.
I made the huge newb error of not including the src files along with the header file. I blame myself. thanks everyone for help
I'm working on an application which defines it's own printf() to get around differences between the different CRTs out there or because some other platforms don't have it.
When building the application with gcc this automatically seems to work and the custom printf is used instead of libc's one; if I understand it correctly this is because of the order in which object files/libraries appear in the link command or maybe because object files are always searched before CRT libs, correct?
I'd like to do the same using msvc. Just building the project gives the expected 'LNK2005: _printf already defined in printf.obj' because printf is also in msvcrtd.lib. Fair enough. I know about /NODEFAULTLIB but that excludes everything resulting in unresolved references for everything but printf. I scanned through the other linker settings but couldn't find anything which allows this (apart from /FORCE maybe, but the 'might produce an invalid executable' comment doesn't make it sound like a good idea). Also nothing in the module definition file docs; the latter got me thinking it might be possible to create a stub library which has all exports from msvcrt.lib except printf but that seems a brittle solution even if it works.
In the end the question is simple: how do I tell msvc's linker it should skip msvcrt's printf definition and use the one from my printf.obj instead. Basically /NODEFAULTFUNCTION:printf or so. Just an answer for one single executable is ok, though I'd also be interested to know if and how it can be done when building a dll instead where the custom printf is exported: how to tell the linker it should use the export from my .lib instead of msvcrt.lib?
edit simplest repo I could find: create a file main.c:
#include <stdio.h>
int main(int argc, char** argv)
{
printf("Hello");
return 0;
}
and a file printf.c:
int printf(const char *fmt, ...)
{
write(1, "ok\n", 3);
return 3;
}
For VS2013 (though the other versions might work as well): create a new empty C++ project and add both files then build. (For gcc: just gcc main.c printf.c and the resulting a.out prints 'ok')
The culptrit for VS is #include : without that it works ok but I have yet to find out if the original code allows getting rid of it in some way. But even if it does I'd still want to know if this can be solved at the link level.
I found a pacman project in github where a file conf.c includes a header file #include "ini.h" where ini.h contains only a single line (i.e no #include statement):
//ini.h
../common/ini.c
I have never seen anyone doing this before! It seems a bit hackish/rough around the edges. My questions are:
Is this legal C?
Is it portable?
Is it recommended?
I would have assumed the answer should be no for all these questions, but I may be learning something new...
edit
From the answers, I see its a Linux symlink. I guess that this means it is not portable to Windows, and would also make it more difficult to read outside a unix environment. I would also imagine that using relative paths (or include directories) instead of symlinks would be a better practice in cases like this for reasons mentioned above...
src/pacman/ini.h is a symbolic link according to the site.
Symbolic link has an information of where the target file is (path name), and I guess it is what is displayed on the site.
The OS will redirect access to that ini.h to ../common/ini.h, which is a normal C code.
I don't see any reason why not. The include statement indicates the compiler to replace that line with the whatever is in the included file
I'm writing some code that uses a C library provided by MATLAB (to extract data from *.mat files). In my IDE (Code::Blocks), I've included the folder containing the necessary "mat.h", which is on a network drive. My code recognises types defined in mat.h when I do this, but whenever I call functions from the file I get an "undefined reference" error. This is the same case for the example code MathWorks provides. What sort of problem usually causes this?
#include "mat.h"
int main (void) {
MATFile *pmat; // Compiles only when compiler is told to search in mat.h directory
pmat = matOpen("example_filename", "r"); // Never compiles
return 0;
}
Thanks!
Cameron
"undefined reference" is normally a linker error. It's not a problem of a header file. You need to tell the linker to link MATLAB's library (or a dedicated object) to your program.
No idea how this is done in Code::Blocks though. In the Code:Blocks documentation it is described here.
Have you checked the contents of mat.h? Does it declare matOpen()? Also, does the error occur when compiling or linking? If it's during the link phase, you probably need to reference the library that contains the implementation of matOpen() (a .lib in Windows, or .a in Unix). The .h file only declares the function.
I'm keep getting this "Unable to resolve identifier file" message on netbeans.
I'm new in c and netbeans.
It was fine last night but somehow after rebooting my computer this message keep occurs.
Here's a code. What would be the problem?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char** argv) {
char filename[] = "text.dat";
char line[5];
FILE *file = fopen(filename, "r");
return 0;
}
I know this is an old post, but I ran into the same issue today. Don't be too quick to assume a compiler-supplied header file is defective. That is rarely the case, especially for headers such as stdio.h that have been around a long time.
Keep in mind that Netbeans code assistance references the includes used within your source code. Any macros that are used by the compiler must be defined to Netbeans. A file such as stdio.h may have conditional includes based on one or more macros. Unless Netbeans is aware of those macros it cannot apply them when it processes include files to provide code assistance. This would prevent conditional headers containing symbols from being loaded.
For example, today I saw that an include file I use has many conditional includes and the symbols Netbeans reported it could not resolve were defined in those files. Knowing that I was building for a particular processor I determined the macro needed for the proper file to be included within . I then defined that macro in Project Properties/Code Assistance/C Compiler/Preprocessor Definitions. At that point Netbeans was able to resolve the symbols.