I have a source file asd.c and the build in rule for compiling and linking this file is not working for some reason.
Here is my super simple makefile:
asd.exe: asd.o
I am getting the following errors
cc -c -o asd.o asd.c
process_begin: CreateProcess(NULL, cc -c -o asd.o asd.c, ...) failed.
make (e=2): The system cannot find the file specified.
<builtin>: recipe for target 'asd.o' failed
mingw32-make: *** [asd.o] Error 2
several possibilities :
there is no file asd.c in the directory containing the makefile/Makefile
you do not have cc or it cannot be found through PATH. Just enter cc by hand in a shell to check
you start make from an other directory, e.g. make -f elsewhere/makefile, in that case asd.c cannot be found
Note that if you only have the line asd.exe: asd.o that will build the executable named asd.o
You can change your makefile like that :
CC = gcc
asd.exe: asd.c
<tab>$(CC) -o asd.exe asd.c
Your simple makefile should suffice, the most probable thing is that make(1) is unable to execute the default rule to compile a .c file, the default compiler is named cc and to change it to use gcc instead, you should change your Makefile to this:
CC=gcc
asd.exe: asd.o
that should work. You can also create a link to cc from gcc (that doesn't hurt, and normally cc is an alias of gcc on sites that have gcc installed as the only compiler)
Indeed, you could make asd just by saying
make asd.exe
with no makefile at all, as there's an implicit rule to generate an executable directly from its .c source file. But also you need to specify the compiler if you don't have cc, so the command should be:
make CC=gcc asd.exe
or, if you are going to always use gcc as your favourite compiler, just create an environment variable CC and assign it gcc in login environment (I'm assuming you are in Windows ---for the .exe extension--- and you know how to include a new environment variable in it)
Related
I have reinstalled mingw in my system and downloaded the gcc compiler.
I was shocked after compiling the first file which was "subject.c" but the name of the compiled file which gcc returned was "a.exe". It should be "subject.exe" but do not know why this happened.
Can anyone please explain the reason behind this ?
expected:
gcc subject.c
ls
subject.c subject.exe
tried:
gcc subject.c
ls
subject.c a.exe
-o can be used to give the name of the output file.
For example,
gcc -Wall -Wextra -pedantic subject.c -o subject.exe
(Do enable your compiler's warnings!)
gcc names its output files, in the absence of other instructions, a.out or a.exe depending on system environment because that is what it's supposed to do.
To override this default behavior, you can use the -o flag which tells gcc that the next argument is the desired name for the output file. For instance:
gcc -o subject.exe subject.c
There is no automatic functionality built into gcc to strip a source file of its file extension and add .exe to the end but this can be done manually with Makefiles or other similar scripts, for instance you can write a Makefile with the following contents:
%.exe: %.c
gcc -o $# $<
Then a command like make subject.exe would be translated to gcc -o subject.exe subject.c, which may be what you're looking for.
There is functionality built into gcc to strip source files of their extensions during different parts of the compilation process, which may have been what confused you. For instance a call like gcc -c subject.c can be expected to produce an object file called subject.o, likewise gcc -S subject.c can be expected to produce an assembly language file called subject.s, however this does not apply to executable files not only for historical reasons, but because programs can be compiled from multiple source files and there is not always a clear way to choose a name for the executable output.
I found a useful library on github for my project, after building this later I tried to use some predefined function on it. I couldn't compile my project because there is some header file missing like this one :
In file included from main.c:2:0:
ptask.h:11:19: fatal error: ptime.h: No such file or directory
I compiled my project using this command :
gcc main.c -L. -lptask
This is all the files in project folder :
libptask.a main.c ptask.h
This is the library content:
$ ar -t libptask.a
pbarrier.c.o
pmutex.c.o
ptask.c.o
ptime.c.o
rtmode.c.o
tstat.c.o
libdl.c.o
dle_timer.c.o
calibrate.c.o
Do I need to add all the headers of this files or just link the lib when compiling ?
Your main.c #include-s ptask.h which in turn #include-s ptime.h. Having compiled static libs alone is not enough (that's the linker's job), you still need to have all used header files (which is the compiler's job), both the ones you use and their dependencies, recursively applicable.
Normally you need to be sure that the header files are in your "include path", something that a lot of compilers define with -I as a command-line option. You'll need to include the source directory of that library, or if it has a make install option, then the place where they got installed.
regarding:
gcc main.c -L. -lptask
this is performing the compile step and the link step in one command.
It is also not enabling the warnings, which should always be enabled during the compile step.
Suggest something similar to the following to compile
gcc -Wall -Wextra -Wconversion -pedantic -std=gnu11 -g -c main.c -o main.o -I.
and when you have fixed all the warnings, then use something similar to the following to link
gcc main.o -o main -L. -lptask
I am currently learning C. I tried to make a makefile, but for some reason, it doesn't work. When I type "make" into the console, the following warnings are printed into the console:
makefile.c:1:1: warning: type specifier missing, defaults to 'int'
[-Wimplicit-int]
CFLAGS=-Wall -g
^~~~~~
makefile.c:1:9: error: use of undeclared identifier 'Wall'
CFLAGS=-Wall -g
^
makefile.c:1:15: error: use of undeclared identifier 'g'
CFLAGS=-Wall -g
^
makefile.c:4:13: error: expected ';' after top level declarator
rm -f ex1
Here is the makefile's code:
CFLAGS=-Wall -g
clean:
rm -f ex1
The code is expected to compile the file ex1.c . Why doesn't my makefile work?
When you run make it tries to figure out what you want it to do.
By default it looks for a file called Makefile or makefile (and for GNU Make, it first looks for GNUMakefile). If it finds such a file, it assumes it is a makefile and reads it.
It seems that here make finds something that looks a bit like a makefile, but then guesses what to do with it. In your case it finds your file makefile.c which it assumes is a source file containing C code, so it uses its built-in rules for processing C source files and tries to compile it with the C compiler. That fails, because your makefile is not a C program! (You lied by naming it makefile.c)
You can either tell make to read that file explicitly (even though it has an unconventional name) by running make -f makefile.c, or you can just give it a sensible name (either Makefile or makefile) so that it gets found automatically when you run make.
When make processes a makefile the first target it finds is the default target. In your makefile the first target is clean so when make runs it will run the rules for the clean target. If you want it to run a different target then either put another target first in the makefile, or specify a target explicitly, e.g. make ex1 (which will cause make to see the file ex1.c and use its built-in rules for compiling a C source file into an executable).
Makefiles are instruction to make, and they are not programs in the same sense as a c-program. From the error messages it looks like you have named your Makefile as a c-source code file, so
Rename your make file to Makefile
mv makefile.c Makefile
Your makefile does not specify what to make -- it only has a clean tag, but not to worry, if your source code is in a single file then make can figure it out, just;
Specify what you want to make
$ make ex1
or alternatively have an entry in your Makefile to do the same, like
CFLAGS=-Wall -g
ex1: ex1.c # This will tell make that ex1 is compiled from ex1.c
clean:
rm -f ex1
A Makefile is not a C file.
You shall rename it from makefile.c to Makefile (mv ./makefile.c ./Makefile)
After on, in your CFLAGS, use -W -ansi -Werror and don't forget to remove the -g when your done, otherwise, your program will be slower on execution.
And then, as it's not a C file, don't try to compile it with gcc
Just type
make
or any other rule you got preceded by make, as
make re; make clean
if you wanna compile the whole thing, then clean trash files (*.o and auto-saves depending on your rules aswell).
Makefile doesn't have extension. Change makefile.c to makefile then try.
Suppose you want create makefile for file1.c & file2.c, here file1.c is depend on file2.c create makefile as given below
makefile: file1.c file2.c
gcc -o makefile file1.c file2.c
And you can just compile using command
make makefile
I resolved the problem by doing the following:
See your all characters in your file, specially in "clean", does not change color even though you saved.
I don't think you saved correctly.
Open gedit and paste your code, then press ctrl + S to save it and then name it to Makefile, not Makefile.c. Makefile is makefile type.
When you save, check file Makefile by clicking the file property. If you see Type: maketype is Ok or see all the characters in your file, the "clean" will change color from grey to another color.
Finally, in terminal, write make clean, not make Makefile. It will run like it does in the "learnCthehardcode" course.
I'm expecting a lot of difficulties to make my program working with the library libmodbus on Linux.
I've installed libmodbus with the command sudo make install and after make but the problem is when I want to link the library in my C program.
My Makefile for now is like:
all: test
test: main.o com.o
gcc main.o com.o -o test
main.o: main.c
gcc -c main.c -o main.o
com.o: com.c
gcc -c com.c -Wl,-rpath=/usr/local/lib -Wl,LIBDIR -o com.o
clean:
rm -rf *o test
In my file com.c I include the file modbus.h like this:
#include <modbus.h>
And I always get the error:
fatal error: modbus.h: No such file or directory.
If it can help when I did make install, the code return me this:
If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the '-LLIBDIR'
flag during linking and do at least one of the following:
add LIBDIR to the `LD_LIBRARY_PATH' environment variable during execution
add LIBDIR to the `LD_RUN_PATH' environment variable during linking
use the `-Wl,-rpath -Wl,LIBDIR' linker flag
have your system administrator add LIBDIR to `/etc/ld.so.conf'
It seems like the modbus.h is not in the standard include directory.
You should to add the -I/<includes_path> flag to gcc options.
I suppose here:
gcc -I/<include_dir_path> -c com.c -Wl,-rpath=/usr/local/lib -Wl,LIBDIR -o com.o
This is the header file and its C file:
cs50.h and
cs50.c
Now I use them in the following example http://www.paste.ubuntu.com/576370/ — which is no longer available.
I already put the header file in /usr/bin/include or something like that and when I try to compile my code using gcc -o xxx xxx.c, it doesn't work, so tried to fix this and the following way worked: http://www.paste.ubuntu.com/576371/ — which is no longer available.
Now I want to do something to make the 'make' command work as the gcc does.
What do I need to do?
The following was the old topic:
I was using gcc command to
compile C programs but after a period
of time I got a problem. I need
to compile a new header file and use
it as a library.
The header file called cs50.h.
so after doing it and it's ok I can
compile using the following
gcc -o xxx xxx.c -lcs50
It works but now I want to use 'make'
command and I can't get it to work.
It just don't compile the header file
and library as gcc was before I edit
it to accept the cs50 library.
So now I want to add to the 'make'
command the following: -lcs50
Can anyone help me in this please?
Near the top of your Makefile, add the line:
LDLIBS = -lcs50
If you are using Make's default (implicit) rules for the building, then that is all you need to do. If you are using explicit rules, you will need to add $(LDLIBS) to your explicit rules.
If there is no Makefile, then make is using default rules, and you can either just create a makefile with
echo LDLIBS = -lcs50 > Makefile
or tell make to link with certain libraries by specifying the required libraries in LDLIBS in the environment. For example, if you are using a sh-derived shell (anything other than csh or tcsh) you can do:
LDLIBS=-lcs50 make target
If you are using a csh variant, you can do:
env LDLIBS=-lcs50 make target
or just do (again, for non-csh shells)
export LDLIBS=-lcs50
before running make. (For csh variants, do setenv LDLIBS -lcs50)
You can use below “make” command to link library and include header directories,
make <.c or .cpp source filename_without_extension> LDLIBS="-l<lib1> -l<lib2>"
suppose you have server.cpp file to compile using make command,
make server LDLIBS="-lcpprest -lpthread -lssl -lcrypto" LDFLAGS="-L/usr/lib/" CXXFLAGS="-I/usr/include/"
Output will expand the compilation command as,
g++ -I/usr/include/ -L/usr/lib/ server.cpp -lcpprest -lpthread -lssl -lcrypto -o server
Did you forget that you have to tell gcc in what directory the CS50 library is located?
gcc … -L/directory/for/cs50_library -lcs50