gcc
and g++
are compiler-drivers of the GNU Compiler Collection (which was once upon a time just the GNU C Compiler).
Even though they automatically determine which backends (cc1
cc1plus
...) to call depending on the file-type, unless overridden with -x language
, they have some differences.
The probably most important difference in their defaults is which libraries they link against automatically.
According to GCC's online documentation link options and how g++ is invoked, g++
is equivalent to gcc -xc++ -lstdc++ -shared-libgcc
(the 1st is a compiler option, the 2nd two are linker options). This can be checked by running both with the -v
option (it displays the backend toolchain commands being run).
By default, Makefile targets are "file targets" - they are used to build files from other files. Make assumes its target is a file, and this makes writing Makefiles relatively easy:
foo: bar
create_one_from_the_other foo bar
However, sometimes you want your Makefile to run commands that do not represent physical files in the file system. Good examples for this are the common targets "clean" and "all". Chances are this isn't the case, but you may potentially have a file named clean
in your main directory. In such a case Make will be confused because by default the clean
target would be associated with this file and Make will only run it when the file doesn't appear to be up-to-date with regards to its dependencies.
These special targets are called phony and you can explicitly tell Make they're not associated with files, e.g.:
.PHONY: clean
clean:
rm -rf *.o
Now make clean
will run as expected even if you do have a file named clean
.
In terms of Make, a phony target is simply a target that is always out-of-date, so whenever you ask make <phony_target>
, it will run, independent from the state of the file system. Some common make
targets that are often phony are: all
, install
, clean
, distclean
, TAGS
, info
, check
.
Best Answer
That's usually because you don't have a file called
vertex.cpp
available to make. Check that:Other than that, I've not much else to suggest. Perhaps you could give us a directory listing of that directory.