Hi all,
I have been going through the k&r2 book and all the examples are done
with main() instead of int main(void) and k&r2 in the start of chapter
1 does not return 0 so I haven't yet either.
I did two compiles shown below.
$ gcc -std=c89 -Wall exercise_1-9.c -o exercise_1-9
exercise_1-9.c:5: warning: return type defaults to `int'
exercise_1-9.c: In function `main':
exercise_1-9.c:27: warning: control reaches end of non-void function
$ gcc -std=c99 -Wall exercise_1-9.c -o exercise_1-9
exercise_1-9.c:5: warning: return type defaults to `int'
Why doesn't k&r2 have the int return type on main and why doesn't c99
care that I reached the end of a non-void function without returning a
value.
Kind Regards,
Anthony Irwin
24  1796 
Anthony Irwin said:
Why doesn't k&r2 have the int return type on main
They rely on the fact that, if a function doesn't explicitly return any
type, it is assumed to return int. This is, in my opinion, poor style.
and why doesn't c99
care that I reached the end of a non-void function without returning a
value.
It does, normally - but they (foolishly?) made a special case for main.
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999 http://www.cpax.org.uk
email: rjh at the above domain, - www.
Richard Heathfield wrote:
Anthony Irwin said:
>>Why doesn't k&r2 have the int return type on main
They rely on the fact that, if a function doesn't explicitly return any
type, it is assumed to return int. This is, in my opinion, poor style.
>>and why doesn't c99
care that I reached the end of a non-void function without returning a
value.
It does, normally - but they (foolishly?) made a special case for main.
Ok thanks for the clarification. I will continue my way through the
k&r2 book which is definately a good book the sample programs they get
you to write seem more real some how, its hard to explain.
Thanks to all who recommended it as I would not have bought it if it
wasn't recommended so much here. Funny how one assumes that a smaller
book won't be as good as a bigger one.
Another quick question is var1 = var2 = var3 = var4 = 0; considered
good style to save typing. I saw it in k&r2 and it was a new concept
for me and I have used it a few types already.
Kind Regards,
Anthony Irwin
Anthony Irwin said:
Another quick question is var1 = var2 = var3 = var4 = 0; considered
good style to save typing. I saw it in k&r2 and it was a new concept
for me and I have used it a few types already.
It's a handy shortcut. I would not recommend using it in too complicated
a way. For example, if you end up typing: a = b += c * a / d = e % f;
then you've probably gone too far.
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999 http://www.cpax.org.uk
email: rjh at the above domain, - www.
Anthony Irwin wrote:
>
.... snip ...
>
Another quick question is var1 = var2 = var3 = var4 = 0;
considered good style to save typing. I saw it in k&r2 and it
was a new concept for me and I have used it a few types already.
Opinions vary. I like it for various reasons. It emphasizes that
those items are initially equal. It may enable more efficient code
to be generated. It minimizes vertical space used.
--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>
--
Posted via a free Usenet account from http://www.teranews.com
Anthony Irwin wrote:
Another quick question is var1 = var2 = var3 = var4 = 0; considered
good style to save typing.
Saving typing is a valid reason for writing code in a certain way,
but it is the weakest of all valid reasons.
The rule is that for the above c code statement,
the assigment of the zero value may be assigned to the vars
in any order. So, make sure to use that kind of code construct,
only when the order of the assignments doesn't matter.
If this is what you mean:
p -next = q;
p = q;
don't write it this way:
p = p -next = q;
--
pete
"Anthony Irwin" <no****@noemail here.nowhereha scritto nel messaggio
news:eu******** **@news-01.bur.connect. com.au...
Why doesn't k&r2 have the int return type on main and why doesn't c99 care
that I reached the end of a non-void function without returning a value.
C99 says that the closing brace of the main() function acts as return 0;},
or something like that (5.1.1.2.3.1).
pete wrote:
Anthony Irwin wrote:
Another quick question is var1 = var2 = var3 = var4 = 0; considered
good style to save typing.
Saving typing is a valid reason for writing code in a certain way,
but it is the weakest of all valid reasons.
The rule is that for the above c code statement,
the assigment of the zero value may be assigned to the vars
in any order. So, make sure to use that kind of code construct,
only when the order of the assignments doesn't matter.
If this is what you mean:
p -next = q;
p = q;
don't write it this way:
p = p -next = q;
What's wrong with the above line? I thought that the assignment
operator has right-left associativity.
CBFalconer wrote:
Anthony Irwin wrote:
... snip ...
Another quick question is var1 = var2 = var3 = var4 = 0;
considered good style to save typing. I saw it in k&r2 and it
was a new concept for me and I have used it a few types already.
Opinions vary. I like it for various reasons. It emphasizes that
those items are initially equal. It may enable more efficient code
to be generated. It minimizes vertical space used.
I'm in the opposite camp. I've never used it in code. I generally feel
that variables that need initialization should be done at declaration
time, and I try to use an individual line for most variable
declarations.
Brian
"CBFalconer " wrote
Anthony Irwin wrote:
>>
... snip ...
>>
Another quick question is var1 = var2 = var3 = var4 = 0;
considered good style to save typing. I saw it in k&r2 and it
was a new concept for me and I have used it a few types already.
Opinions vary. I like it for various reasons. It emphasizes that
those items are initially equal. It may enable more efficient code
to be generated. It minimizes vertical space used.
True, but most modern compilers can optimize away whitespace
and carriage returns.
--
Craig Franck cr**********@ve rizon.net
Cortland, NY This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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--------------------------------- PROGRAMME
--------------------------------
/* K&R2 section 1.9
exercise 1.19
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