I am using codeblock 13.12 and it uses mingw (GCC 4.7 & 4.8 Series)
It supports call by reference (func1(int &a)) eventhough I am selecting C project and not CPP project. If I am not mistaken, there is no concept of call by reference in C and everything is call by value even if it is making use of pointers.
My question is how to use C only features? Any settings for this? I saw that in toolchain it is using mingw32-gcc.exe for c compilations.
How to know which compiler version (Like C11, C99 etc) it is really using?
Name your files with an extension of .c. And definitely not .cc or .cpp
Compile with gcc as the command line, not g++
And if in doubt, use the -std= command line parameter to force the flavor of C you want (e.g. -std=C90, -std=C99, or even -std=C11 ). There's also -ansi.
Also, a cheap and dirty way to validate if your code is getting compiled as C and not C++ is to add this block of code within your source code. If it's C++, then the compiler will generate an error.
#ifdef __cplusplus
int compile_time_assert[-1];
#endif
Related
Given a meson-based project where meson.build contains the following line:
cc = meson.get_compiler('c')
How does meson.get_compiler('c') pick a compiler on a system with multiple C compilers? At the time of writing this question, the reference manual does not provide much detail, only...
Returns a compiler object describing a compiler.
Please note I am not trying to force meson to use a specific compiler. Rather, I am trying to understand how this line in meson.build, as it is currently written, will function.
On Windows it tries icl, cl, cc, gcc, clang, clang-cl, pgcc; on Linux it tries cc, gcc, clang, nvc, pgc, icc. That's after it looks for the value of $CC and whatever is in your cross or native file. See the code here.
I'm trying to compile some c-code that was originally written for SDCC using GCC to run some unit tests on a host computer.
There are some language extensions for SDCC like __xdata or __pdata (for memory control) which should remain for SDCC but that should be ignored when compiled with GCC. I would strongly prefer not to modify the modules under test. Is there any way to do this?
I already figured out that it works if I add something like #define __xdata in the module under test. Maybe it is possible to have something like a "global definition" therefore? I have little experience with the GCC. Maybe there are compiler flags that could help me?
There are two compiler flags, you could use:
-include allows you to give a c file that is additionally included and do the defines in that file.
Define macros via command line options -D__xdata=
I am trying to compile a C source code to a machine code using an ubunto terminal
My tutor instruction was to use the following command:
running clang myprogramm.c -std=c11
Why shall I use the keyword -std=c11 and what is the difference to using just
clang myprogramm.c
Using std= options is required by your tutor (I'm divinig her motives, I'm particularly good at this!) because she wants to make sure you stay away from all those nifty Clang features that turn the accepted language from C to A LANGUAGE SUPERFICIALLY LOOKING LIKE C BUT ACTUALLY A DIFFERENT LANGUAGE NOT SUPPORTED BY OTHER C COMPILERS.
That is more than just additional library functions. It include syntax changes that break the grammar of Standard C, as defined by ISO. A grasshopper should not use these while learning. Using -std=c11 makes sure Clang either warns about or even rejects, with an error, such constructs.
When to specify the standard? Whenever you use the compiler. It is never a good idea to let the compiler just use whatever it wants.
If someone tries to use a compiler that is too old, then they will get a warning or error, and they will understand why the compile fails.
If a code contributor (maybe even yourself!) tries to add code using features that are too new, their code will be rejected. That's very important if you intend to keep compatibility with an older standard.
By explicitly stating the standard, using new features or extensions are a choice and don't happen by accident.
Is there any way to compile C code with c89 standard NOT c99 in Xcode (or another way with terminal)?
I've searched in Xcode settings but I didn't find any way to choose compiler or standard.
You should add -pedantic-errors to Other C flags in your project settings, like so:
Of course, don't forget to set the C language dialect to C89 as well.
This will give you the appropriate compile time errors when you try to compile something that is not valid C89.
Optionally, if you want Xcode to compile your code regardless of incompatibilities, but only give you yellow warnings at the problematic lines, use -pedantic instead of -pedantic-errors.
In a nutshell, these flags make the compiler stick to the language standard more strictly, as opposed to the default behavior, which is to attempt compiling the code any way possible.
I hope this helps :)
Source
(even though they mention this in the context of GCC, but the same flags apply for Clang as well)
I am trying to compile some C code on a beagleboard xm. I try to compile, but I get the error: undefined reference to 'isfinite' which is in the math.h library. This code compiles perfectly in all my other computers, and I do include -lm in my makefile.
I suspect that it may be my compiler, maybe it is an over version? On the beagleboard it's version 4.3.3, but on my computer it's 4.7.3, but I don't know how to get a later version. I thought opkg would automatically get the latest available.
Any ideas why this may be happening?
The function infinite() is part of C99. Your compiler is by default using an older version of the C language. You need to compile with the the flag -std=c99 to enable this macro.
`gnu89' GNU dialect of ISO C90 (including some C99 features). This is
the default for C code.
http://gcc.gnu.org/onlinedocs/gcc-4.3.3/gcc/C-Dialect-Options.html
isfinite is part of the C++11 standard and gcc 4.3.3 is to old to know that. Try
int finite(double x); or int finitef(float x);.