Is there a way to initialize the variables (or other data) of a header
file by using a function (similar to main() function)??
Thankx
file by using a function (similar to main() function)??
Thankx
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Re: Initialize Variables of a Header File
On Mar 15, 4:02 pm, Ramon <ramif...@yahoo .co.ukwrote:I'm not sure I understand your question. IMO, variablesIs there a way to initialize the variables (or other data) of a header
file by using a function (similar to main() function)??
should only be declared in a header, and not defined,
so it makes little sense to attempt to initialize them.
What prevents you from doing:
int x;
int main( void )
{
initialize_x();
...
I get the impression that you are trying instead to do:
/* myfile.h */
int x = initialize_x();
and this is a very bad idea, indeed, since header
files should be able to be included in multiple
translation units...do you want the initialize_x()
function to run multiple times?
What exactly are you trying to do?
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Re: Initialize Variables of a Header File
Ramon <ramif_47@yahoo .co.ukwrites:
Sure. Write a function to initialize your variables, then callIs there a way to initialize the variables (or other data) of a header
file by using a function (similar to main() function)??
it.
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=b,i=24;for(;p+ =!*p;*p/=4)switch(0[p]&3)case 0:{return 0;for(p--;i--;i--)case+
2:{i++;if(i)bre ak;else default:continu e;if(0)case 1:putchar(a[i&15]);break;}}}
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Re: Initialize Variables of a Header File
William Pursell wrote:Sorry for not being clear.On Mar 15, 4:02 pm, Ramon <ramif...@yahoo .co.ukwrote:>>Is there a way to initialize the variables (or other data) of a header
>file by using a function (similar to main() function)??
I'm not sure I understand your question. IMO, variables
should only be declared in a header, and not defined,
so it makes little sense to attempt to initialize them.
What prevents you from doing:
>
int x;
int main( void )
{
initialize_x();
...
>
>
I get the impression that you are trying instead to do:
/* myfile.h */
int x = initialize_x();
>
and this is a very bad idea, indeed, since header
files should be able to be included in multiple
translation units...do you want the initialize_x()
function to run multiple times?
>
What exactly are you trying to do?
>
I've tried to initialize variables in a header file by doing something
like this:
#ifndef HANDSHAKING_H_
#define HANDSHAKING_H_
..
..
..
int nextHS = 0; // location of next element of handshakeList
..
..
..
#endif /*HANDSHAKING_H_ */
By doing this, the linker complains and apparently it is not acceptable
in gcc (version 4.1.1-21).
My question is:
Can I write a function that is called /automatically/ by the compiler
and that initializes all my variables that are in the header file
(somewhat similar to main() function of a normal C program) ?
And if I can write such a function, how can I implement it?
Thankx in advance!
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Re: Initialize Variables of a Header File
On Sat, 15 Mar 2008 17:48:43 +0100, Ramon wrote:So when you have two files that include that header, you have two filesSorry for not being clear.
>
I've tried to initialize variables in a header file by doing something
like this:
>
>
#ifndef HANDSHAKING_H_
#define HANDSHAKING_H_
.
.
.
int nextHS = 0; // location of next element of handshakeList .
.
.
#endif /*HANDSHAKING_H_ */
that define nextHS.
You should usually post the exact error message. In this case, theBy doing this, the linker complains and apparently it is not acceptable
in gcc (version 4.1.1-21).
problem is apparent from the code itself, but when it's not, the error
message can clarify a lot.
No. But you don't need one, see below.My question is:
Can I write a function that is called /automatically/ by the compiler
and that initializes all my variables that are in the header file
(somewhat similar to main() function of a normal C program) ?
In your handshaking.h, putAnd if I can write such a function, how can I implement it?
extern int nextHS;
In _one_ source file, put
int nextHS = 0;
The linker tells you that you have multiple definitions of nextHS, so
this way, you make sure you only have one definition.
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Re: Initialize Variables of a Header File
Ramon <ramif_47@yahoo .co.ukwrites:
This is not the way you do it. Instead, write "extern intI've tried to initialize variables in a header file by doing something
like this:
>
>
#ifndef HANDSHAKING_H_
#define HANDSHAKING_H_
.
.
.
int nextHS = 0; // location of next element of handshakeList
.
.
.
#endif /*HANDSHAKING_H_ */
nextHS;" in the header file and "int nextHS = 0;" in exactly one
C source file (not header file).
--
"I ran it on my DeathStation 9000 and demons flew out of my nose." --Kaz
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Re: Initialize Variables of a Header File
On 15 Mar, 16:48, Ramon <ramif...@yahoo .co.ukwrote:AFAIK, you cannot do that in standard C. However, gccWilliam Pursell wrote:>On Mar 15, 4:02 pm, Ramon <ramif...@yahoo .co.ukwrote:Is there a way to initialize the variables (or other data) of a header
file by using a function (similar to main() function)??>I'm not sure I understand your question. IMO, variables
should only be declared in a header, and not defined,
so it makes little sense to attempt to initialize them.
What prevents you from doing:>int x;
int main( void )
{
initialize_x();
...>I get the impression that you are trying instead to do:
/* myfile.h */
int x = initialize_x();>and this is a very bad idea, indeed, since header
files should be able to be included in multiple
translation units...do you want the initialize_x()
function to run multiple times?>What exactly are you trying to do?
Sorry for not being clear.
>
I've tried to initialize variables in a header file by doing something
like this:
>
#ifndef HANDSHAKING_H_
#define HANDSHAKING_H_
.
.
.
int nextHS = 0; // location of next element of handshakeList
.
.
.
#endif /*HANDSHAKING_H_ */
>
By doing this, the linker complains and apparently it is not acceptable
in gcc (version 4.1.1-21).
>
My question is:
Can I write a function that is called /automatically/ by the compiler
and that initializes all my variables that are in the header file
(somewhat similar to main() function of a normal C program) ?
>
And if I can write such a function, how can I implement it?
allows you to identify functions which are called prior
to main():
void __attribute__(( constructor))
initialize (void)
{
/* code that executes before main */
}
IMO, you are better off just calling the initialization
function yourself...it makes for clearer code and there's
no gain whatsoever in using tricks like this.
However, you keep using the phrase "variables ... in
the header file". Only declarations should appear in the
header file; the definition should not be in the header.
(eg, in the header, you should have the word "extern"
on each variable declaration.)
There is a common style to use headers simply
as textual replacement to minimize the amount
of cruft at the start of the .c file, but that's
not really what they're for. If you have a lot
of global variables and you are trying to hide
the declarations/definitions, consider something
like:
a.h:
extern int x;
a.c:
#include "a.h"
int main(void) { /* use x */ }
x.c:
int x;
$ gcc -c x.c && gcc -c a.c && gcc a.o x.o
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