Re: #include in a C file

[ali hagigat]

Dear Sam,
You never answered my latest questions!!
Does this rule have a recipe?!!:
main.o main.d : main.c defs.h

On 12/6/10, Sam Ravnborg <address@hidden> wrote:
> On Mon, Dec 06, 2010 at 11:02:38AM +0330, ali hagigat wrote:
>> In section 4.13, we have the following example:
>> ----------------------------------------------------------
>> %.d: %.c
>> @set -e; rm -f $@; \
>> $(CC) -M $(CPPFLAGS) $< > address@hidden; \
>> sed ’s,\($*\)\.o[ :]*,\1.o $@ : ,g’ < address@hidden > $@; \
>> rm -f address@hidden
>> ----------------------------------------------------------
>> Under what conditions this implicit rule is executed?
>> Would you please give an example?
>>
>> Why the 'sed' command is necessary? and why we need to have the following
>> rule:
>> main.o main.d : main.c defs.h
>> Can the command, 'sed' be replaced with:
>> cp address@hidden $@
>> (I mean we have one .d file for each .c file and it will be included,
>> why we need a rule like   main.d : main.c defs.h? This rule is without
>> recipe and what is it supposed to do?)
>
> Sorry Ali.
> I have tried to explain things but obvioulsy without luck.
> Please go ahead and try out the things described - and _then_ ask questions.
> I guess you would then figure out that the above has a receipe,
> the purpose of sed etc.
>
> Until then,
>
>       Sam
>