Tell me about makefiles

[=?ISO-8859-1?Q?Tom=E1s_=D3_h=C9ilidhe?=]

I already understand how program compilation works (i.e. the
preprocessor produces individual translation units which get compiled
separately, and then the linker links the object files together), but
I don't know anything about makefiles.

If I had the following program:

/* main.c */

extern void Func(void);

int main(void)
{
Func();
return 0;
}

/* func.c */

#include <stdio.h>

void Func(void) { puts("Hello World!"); }

/* End of code */

, then I would compile it as follows with gcc:

gcc a.c b.c -ansi -pedantic -s -O3 -D NDEBUG -o prog.exe

What would my makefile for this look like?

[Eric Sosman]

Re: Tell me about makefiles

Tomás Ó hÉilidhe wrote:

I already understand how program compilation works (i.e. the
preprocessor produces individual translation units which get compiled
separately, and then the linker links the object files together), but
I don't know anything about makefiles.
>
If I had the following program:
[...]
What would my makefile for this look like?

It would look like something better discussed on
comp.unix.progr ammer than here.

--
Eric Sosman
esosman@ieee-dot-org.invalid

[Richard Heathfield]

Re: Tell me about makefiles

Tomás Ó hÉilidhe said:

<snip>

gcc a.c b.c -ansi -pedantic -s -O3 -D NDEBUG -o prog.exe
>
What would my makefile for this look like?

I don't know, but mine would look like this:

CC=gcc
CFLAGS=-W -Wall -ansi -pedantic -Wformat-nonliteral -Wcast-align
-Wpointer-arith -Wbad-function-cast -Wmissing-prototypes
-Wstrict-prototypes -Wmissing-declarations -Winline -Wundef
-Wnested-externs -Wcast-qual -Wshadow -Wconversion -Wwrite-strings
-ffloat-store -O2
DFLAGS=-g -pg
a: a.o b.o
$(CC) $(CFLAGS) $(DFLAGS) -o prog.exe a.o b.o
a.o: a.c
$(CC) $(CFLAGS) $(DFLAGS) -c -o a.o a.c
b.o: b.c
$(CC) $(CFLAGS) $(DFLAGS) -c -o b.o b.c

clean:
rm a.o
rm b.o
rm prog.exe

install:
cp prog.exe /usr/local/bin


Note that, in a "real" makefile, the indented lines start with a HARD TAB
(ASCII 9) character.

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[Richard Heathfield]

Re: Tell me about makefiles

Eric Sosman said:

Tomás Ó hÉilidhe wrote:

>What would my makefile for this look like?

>
It would look like something better discussed on
comp.unix.progr ammer than here.

What makes you think he's using Unix?

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[santosh]

Re: Tell me about makefiles

Tomás Ó hÉilidhe wrote:

>
I already understand how program compilation works (i.e. the
preprocessor produces individual translation units which get compiled
separately, and then the linker links the object files together), but
I don't know anything about makefiles.
>
If I had the following program:
>
/* main.c */
>
extern void Func(void);

This is not related to your question, but isn't the above declaration
unnecessary seeing as functions have external linkage unless specified
otherwise?

int main(void)
{
Func();
return 0;
}
>
/* func.c */
>
#include <stdio.h>
>
void Func(void) { puts("Hello World!"); }
>
/* End of code */
>
, then I would compile it as follows with gcc:
>
gcc a.c b.c -ansi -pedantic -s -O3 -D NDEBUG -o prog.exe
>
What would my makefile for this look like?

[Ian Collins]

Re: Tell me about makefiles

santosh wrote:

Tomás Ó hÉilidhe wrote:
>

>I already understand how program compilation works (i.e. the
>preprocessor produces individual translation units which get compiled
>separately, and then the linker links the object files together), but
>I don't know anything about makefiles.
>>
>If I had the following program:
>>
>/* main.c */
>>
>extern void Func(void);

>
This is not related to your question, but isn't the above declaration
unnecessary seeing as functions have external linkage unless specified
otherwise?

No, if you look again, he's defining the function in another compilation
unit.

--
Ian Collins.

[Harald van =?UTF-8?b?RMSzaw==?=]

Re: Tell me about makefiles

On Sat, 08 Mar 2008 03:13:56 +0530, santosh wrote:

Tomás Ó hÉilidhe wrote:

>I already understand how program compilation works (i.e. the
>preprocessor produces individual translation units which get compiled
>separately, and then the linker links the object files together), but I
>don't know anything about makefiles.
>>
>If I had the following program:
>>
>/* main.c */
>>
>extern void Func(void);

>
This is not related to your question, but isn't the above declaration
unnecessary seeing as functions have external linkage unless specified
otherwise?

The declaration is necessary. The extern keyword in the declaration is
unnecessary. (I'm sure that's what you meant.)

However, some coding styles do use the extern keyword to declare functions
that are defined in a different unit, in the same way that the keyword is
used to declare objects that are defined in a different unit. It's not
required, but it's perfectly valid C, and no less readable than its
shortened equivalent.

[santosh]

Re: Tell me about makefiles

Harald van D?k wrote:

On Sat, 08 Mar 2008 03:13:56 +0530, santosh wrote:

>Tomás Ó hÉilidhe wrote:

>>I already understand how program compilation works (i.e. the
>>preprocesso r produces individual translation units which get
>>compiled separately, and then the linker links the object files
>>together), but I don't know anything about makefiles.
>>>
>>If I had the following program:
>>>
>>/* main.c */
>>>
>>extern void Func(void);

>>
>This is not related to your question, but isn't the above declaration
>unnecessary seeing as functions have external linkage unless
>specified otherwise?

>
The declaration is necessary. The extern keyword in the declaration is
unnecessary. (I'm sure that's what you meant.)

Yes, sorry, that's what I meant. It's very late here.

However, some coding styles do use the extern keyword to declare
functions that are defined in a different unit, in the same way that
the keyword is used to declare objects that are defined in a different
unit. It's not required, but it's perfectly valid C, and no less
readable than its shortened equivalent.

I see. Thanks.

[Antoninus Twink]

Re: Tell me about makefiles

On 7 Mar 2008 at 21:34, Richard Heathfield wrote:

Tomás Ó hÉilidhe said:
>
><snip>
>

>gcc a.c b.c -ansi -pedantic -s -O3 -D NDEBUG -o prog.exe
>>
>What would my makefile for this look like?

>
I don't know, but mine would look like this:
>
CC=gcc
CFLAGS=-W -Wall -ansi -pedantic -Wformat-nonliteral -Wcast-align
-Wpointer-arith -Wbad-function-cast -Wmissing-prototypes
-Wstrict-prototypes -Wmissing-declarations -Winline -Wundef
-Wnested-externs -Wcast-qual -Wshadow -Wconversion -Wwrite-strings
-ffloat-store -O2
DFLAGS=-g -pg
a: a.o b.o
$(CC) $(CFLAGS) $(DFLAGS) -o prog.exe a.o b.o
a.o: a.c
$(CC) $(CFLAGS) $(DFLAGS) -c -o a.o a.c
b.o: b.c
$(CC) $(CFLAGS) $(DFLAGS) -c -o b.o b.c
>
clean:
rm a.o
rm b.o
rm prog.exe
>
install:
cp prog.exe /usr/local/bin

Is this a joke? That's one of the most amateurish makefiles I've ever
seen.

[Robbie Hatley]

Re: Tell me about makefiles


"Tomás Ó hÉilidhe" wrote:

I don't know anything about makefiles ...
... What would my makefile for this look like? ...

Off-topic here; ask this question in the following newsgroup:

gnu.utils.help

Also read the O'Reilly book "Managing Projects with Gnu Make"
(available at computer stores, bookstores, and amazon.com).

Also try these googles:

gnu make
makefile

--
Cheers,
Robbie Hatley
lonewolf aatt well dott com
www dott well dott com slant user slant lonewolf slant

[Richard Harter]

Re: Tell me about makefiles

On Fri, 7 Mar 2008 23:46:34 +0100 (CET), Antoninus Twink
<nospam@nospam. invalidwrote:

>On 7 Mar 2008 at 21:34, Richard Heathfield wrote:

>Tomás Ó hÉilidhe said:
>>
>><snip>
>>

>>gcc a.c b.c -ansi -pedantic -s -O3 -D NDEBUG -o prog.exe
>>>
>>What would my makefile for this look like?

>>
>I don't know, but mine would look like this:
>>
>CC=gcc
>CFLAGS=-W -Wall -ansi -pedantic -Wformat-nonliteral -Wcast-align
>-Wpointer-arith -Wbad-function-cast -Wmissing-prototypes
>-Wstrict-prototypes -Wmissing-declarations -Winline -Wundef
>-Wnested-externs -Wcast-qual -Wshadow -Wconversion -Wwrite-strings
>-ffloat-store -O2
>DFLAGS=-g -pg
>a: a.o b.o
> $(CC) $(CFLAGS) $(DFLAGS) -o prog.exe a.o b.o
>a.o: a.c
> $(CC) $(CFLAGS) $(DFLAGS) -c -o a.o a.c
>b.o: b.c
> $(CC) $(CFLAGS) $(DFLAGS) -c -o b.o b.c
>>
>clean:
> rm a.o
> rm b.o
> rm prog.exe
>>
>install:
> cp prog.exe /usr/local/bin

>
>Is this a joke? That's one of the most amateurish makefiles I've ever
>seen.
>

Is it now? I'm willing to have my mind illuminated. Do tell,
why is it "most amateruish"? Don't just make snarky comments,
explain yourself.



Richard Harter, cri@tiac.net
http://home.tiac.net/~cri, http://www.varinoma.com
Save the Earth now!!
It's the only planet with chocolate.

[Antoninus Twink]

Re: Tell me about makefiles

On 7 Mar 2008 at 23:29, Richard Harter wrote:

On Fri, 7 Mar 2008 23:46:34 +0100 (CET), Antoninus Twink
><nospam@nospam .invalidwrote:
>

>>On 7 Mar 2008 at 21:34, Richard Heathfield wrote:

>>Tomás Ó hÉilidhe said:
>>>
>>><snip>
>>>
>>>gcc a.c b.c -ansi -pedantic -s -O3 -D NDEBUG -o prog.exe
>>>>
>>>What would my makefile for this look like?
>>>
>>I don't know, but mine would look like this:
>>>
>>CC=gcc
>>CFLAGS=-W -Wall -ansi -pedantic -Wformat-nonliteral -Wcast-align
>>-Wpointer-arith -Wbad-function-cast -Wmissing-prototypes
>>-Wstrict-prototypes -Wmissing-declarations -Winline -Wundef
>>-Wnested-externs -Wcast-qual -Wshadow -Wconversion -Wwrite-strings
>>-ffloat-store -O2
>>DFLAGS=-g -pg
>>a: a.o b.o
>> $(CC) $(CFLAGS) $(DFLAGS) -o prog.exe a.o b.o
>>a.o: a.c
>> $(CC) $(CFLAGS) $(DFLAGS) -c -o a.o a.c
>>b.o: b.c
>> $(CC) $(CFLAGS) $(DFLAGS) -c -o b.o b.c
>>>
>>clean:
>> rm a.o
>> rm b.o
>> rm prog.exe
>>>
>>install:
>> cp prog.exe /usr/local/bin

>>
>>Is this a joke? That's one of the most amateurish makefiles I've ever
>>seen.
>>

>
Is it now? I'm willing to have my mind illuminated. Do tell,
why is it "most amateruish"? Don't just make snarky comments,
explain yourself.

To take the most trivial points:
1) doesn't take advantage of built-in rules
2) highly non-extensible - should define, say, $(OBJECTS) instead of
listing all the object files in more than one place.
3) should rm -f so that "make clean" doesn't return a non-zero value
when called with no built files present
4) "make install" fails to set permissions sensibly (most likely 755
will be wanted for a program in /usr/local/bin) - and it would be nice
to have a $(PREFIX) variable instead of hard-coding the path
5) WTF is "DFLAGS"? A non-standard variable name, with no comment
explaining what it's for.

[Richard Tobin]

Re: Tell me about makefiles

In article <slrnft3kjd.g85 .nospam@nospam. invalid>,
Antoninus Twink <nospam@nospam. invalidwrote:

>>>DFLAGS=-g -pg

>5) WTF is "DFLAGS"? A non-standard variable name, with no comment
>explaining what it's for.

It's obviously "debug flags".

-- Richard



--
:wq

[Default User]

Re: Tell me about makefiles

Richard Harter wrote:

On Fri, 7 Mar 2008 23:46:34 +0100 (CET), Antoninus Twink
<nospam@nospam. invalidwrote:

Is this a joke?

Is it now?

Twink is troll. More specfically, he is one that is netstalking Mr.
Heathfield. Killfile or ignore, is my recommendation.





Brian

[CBFalconer]

Re: Tell me about makefiles

Richard Harter wrote:

Antoninus Twink <nospam@nospam. invalidwrote:

>Richard Heathfield wrote:
>>

.... snip ...

>>

>>I don't know, but mine would look like this:
>>>
>>CC=gcc
>>CFLAGS=-W -Wall -ansi -pedantic -Wformat-nonliteral -Wcast-align
>>-Wpointer-arith -Wbad-function-cast -Wmissing-prototypes
>>-Wstrict-prototypes -Wmissing-declarations -Winline -Wundef
>>-Wnested-externs -Wcast-qual -Wshadow -Wconversion -Wwrite-strings
>>-ffloat-store -O2
>>DFLAGS=-g -pg
>>a: a.o b.o
>> $(CC) $(CFLAGS) $(DFLAGS) -o prog.exe a.o b.o
>>a.o: a.c
>> $(CC) $(CFLAGS) $(DFLAGS) -c -o a.o a.c
>>b.o: b.c
>> $(CC) $(CFLAGS) $(DFLAGS) -c -o b.o b.c
>>>
>>clean:
>> rm a.o
>> rm b.o
>> rm prog.exe
>>>
>>install:
>> cp prog.exe /usr/local/bin

>>
>Is this a joke? That's one of the most amateurish makefiles
>I've ever seen.

>
Is it now? I'm willing to have my mind illuminated. Do tell,
why is it "most amateruish"? Don't just make snarky comments,
explain yourself.

You realize you are talking to a prime troll?

At any rate, it is a fine example. The only criticism I would make
is that the dependencies for a.o and b.o do not include a.h and
b.h.

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.


--
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