global struct declarations

[Elliot Marks]

If a struct or its members are passed
to a function, must it be declared globally?

#include <stdio.h>
struct mystruct{
int a;
int b;
};
int structfunc(stru ct mystruct foo);

int main(void)
{
struct mystruct bar;
bar.a = 123;
bar.b = 456;
int sum = structfunc(bar) ;
printf("%d\n", sum);

return 0;
}

int structfunc(stru ct mystruct foo)
{
int sum = foo.a + foo.b;
return sum;
}

This code doesn't compile if the struct
declaration is moved inside main().

[Mark A. Odell]

"Frane Roje" <frane.roje(d*e lete*)@st.hinet .hr> wrote in
news:bt******** **@ls219.htnet. hr:

I've never seen a declaration of struct inside a function.
I do it all the time. If I need to package up some common set of data
inside a function to make it more clear I do. Why should I expose the
struct declaration outside the function?
I believe it's
not common and there is no reason why should anyone declare it inside a
function.

Yes there is, it is no use to other functions.

See how your top posting destroyed the thread?

--
- Mark ->
--

[Frane Roje]

"Frane Roje" <frane.roje(d*e lete*)@st.hinet .hr> wrote in message
news:bt******** **@ls219.htnet. hr...

Well we're all here to learn, I'm glad I said what I said 'cause now I know more!

I use VC7 and i wrote a code with a struct inside main() and it >did not show up in the class view, does it appear in your editor? If I declare a global
struct i does show in the class view.

I forgot to mention that it does complie and work with a struct inside
function
--

---------------------------
Time to get it done!

Remove (d*elete*) to reply

[Frane Roje]

And 1 more thing

int sum = structfunc(bar) ;

This code is C++ maybe that is why the code won't compile

--

---------------------------
Time to get it done!

Remove (d*elete*) to reply

[Frane Roje]

Well we're all here to learn, I'm glad I said what I said 'cause now I know
more!

I use VC7 and i wrote a code with a struct inside main() and it did not show
up in the class view, does it appear in your editor? If I declare a global
struct i does show in the class view.

--

---------------------------
Time to get it done!

Remove (d*elete*) to reply

"Mark A. Odell" <no****@embedde dfw.com> wrote in message
news:Xn******** *************** *********@130.1 33.1.4...

"Frane Roje" <frane.roje(d*e lete*)@st.hinet .hr> wrote in
news:bt******** **@ls219.htnet. hr:

I've never seen a declaration of struct inside a function.

I do it all the time. If I need to package up some common set of data
inside a function to make it more clear I do. Why should I expose the
struct declaration outside the function?

I believe it's
not common and there is no reason why should anyone declare it inside a
function.

Yes there is, it is no use to other functions.

See how your top posting destroyed the thread?

--
- Mark ->
--

[Frane Roje]

I've never seen a declaration of struct inside a function. I believe it's
not common and there is no reason why should anyone declare it inside a
function.
And your code is strange. It seems that you are using a little bit of C and
C++. Everything looks like C except for the
int sum = structfunc(bar) ; which is C++ code.

--

---------------------------
Time to get it done!

Remove (d*elete*) to reply

"Elliot Marks" <em****@email.n et> wrote in message
news:3F******** ******@email.ne t...

If a struct or its members are passed
to a function, must it be declared globally?

#include <stdio.h>
struct mystruct{
int a;
int b;
};
int structfunc(stru ct mystruct foo);

int main(void)
{
struct mystruct bar;
bar.a = 123;
bar.b = 456;
int sum = structfunc(bar) ;
printf("%d\n", sum);

return 0;
}

int structfunc(stru ct mystruct foo)
{
int sum = foo.a + foo.b;
return sum;
}

This code doesn't compile if the struct
declaration is moved inside main().

[Alex Monjushko]

Elliot Marks <em****@email.n et> wrote:

If a struct or its members are passed
to a function, must it be declared globally?
Yes for struct. No for members.
#include <stdio.h>
struct mystruct{
int a;
int b;
};
int structfunc(stru ct mystruct foo); int main(void)
{
struct mystruct bar;
bar.a = 123;
bar.b = 456;
int sum = structfunc(bar) ;
Unless you are using C99, you cannot intermix declarations
and statements.
printf("%d\n", sum); return 0;
} int structfunc(stru ct mystruct foo)
{
int sum = foo.a + foo.b;
return sum;
} This code doesn't compile if the struct
declaration is moved inside main().

Of course it doesn't compile. By declaring 'mystruct' in main,
you can only use it main. It is no longer visible to 'structfunc'.

--
Alex Monjushko (mo*******@hotm ail.com)

[CBFalconer]

Elliot Marks wrote:

If a struct or its members are passed
to a function, must it be declared globally?

#include <stdio.h>
struct mystruct{
int a;
int b;
};
int structfunc(stru ct mystruct foo);

int main(void)
{
struct mystruct bar;
bar.a = 123;
bar.b = 456;
int sum = structfunc(bar) ;
printf("%d\n", sum);

return 0;
}

int structfunc(stru ct mystruct foo)
{
int sum = foo.a + foo.b;
return sum;
}

This code doesn't compile if the struct
declaration is moved inside main().

That is because it is not a declaration, but a type definition.
That definition is not visible outside the source file.

--
Chuck F (cb********@yah oo.com) (cb********@wor ldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net> USE worldnet address!

[Mark A. Odell]

"Frane Roje" <frane.roje(d*e lete*)@st.hinet .hr> wrote in
news:bt******** **@ls219.htnet. hr:

Well we're all here to learn, I'm glad I said what I said 'cause now I

know

more!

I use VC7 and i wrote a code with a struct inside main() and it >did not

show

up in the class view, does it appear in your editor? If I declare a
global struct i does show in the class view.

I forgot to mention that it does complie and work with a struct inside
function

Of course, it's legal :-). I never use IDEs except for building and
debugging code. That is I edit with my editor and the ALT-TAB to the IDE
and push the build button, then debug. I use CodeWright (now owned by
Borland) and it does show all structs, local or otherwise.

--
- Mark ->
--

[Chris Torek]

[top-posting fixed]

"Elliot Marks" <em****@email.n et> wrote in message
news:3F******* *******@email.n et...

If a struct or its members are passed
to a function, must it be declared globally?
Any type must be declared at a scope such that its declaration is
visible to everyone using it. In this case, if some file(s) are
passing or returning entire structs, those structs must be declared
at file scope.

(Remember that "struct foo" is how you define a new type in C.
Some people like to decorate this with an additional "typedef",
but the typedef does NOT define a new type, just an alias for it.
The "struct" keyword is the one that defines the type!)

In article <bt**********@l s219.htnet.hr>
Frane Roje <frane.roje(d*e lete*)@st.hinet .hr> wrote:

I've never seen a declaration of struct inside a function. I believe it's
not common and there is no reason why should anyone declare it inside a
function.

One declares types (such as new "struct"s) inside functions for
the same reason one declares anything inside functions: to restrict
the scope of the type-names, variables, and so forth.

[Elliot Marks] #include <stdio.h>
struct mystruct{
int a;
int b;
};
int structfunc(stru ct mystruct foo);

int main(void)
{
struct mystruct bar;
bar.a = 123;
bar.b = 456;
int sum = structfunc(bar) ;
Note that this syntax (which does look a lot like C++, as Frane Roje
noted) is new in C99.
printf("%d\n", sum);

return 0;
}

int structfunc(stru ct mystruct foo)
{
int sum = foo.a + foo.b;
return sum;
}

This code doesn't compile if the struct
declaration is moved inside main().

The "struct mystruct" type needs to be in scope for both the
prototype declaration of "structfunc " and for the definition
of "structfunc ". You can achieve the former even with a block-scope
definition of the struct by putting the prototype inside main()
as well; but the latter requires "struct mystruct" to occur at
file scope.

Remember, type declarations and definitions have scope, just like
ordinary variable declarations. (But type names do not have linkage,
unlike ordinary variables.)
--
In-Real-Life: Chris Torek, Wind River Systems
Salt Lake City, UT, USA (40°39.22'N, 111°50.29'W) [phone]
email: forget about it http://web.torek.net/torek/index.html
Reading email is like searching for food in the garbage, thanks to spammers.