C++ and Arduino Functions

Forum 2005-2010 (read only) Software Syntax & Programs
1

So, I'm trying to create a class to subclass and allow for a simplistic run loop to allow me to simulate "threads." Each item will have the ability to basically say "don't run again for xx microseconds." For this, I need the "micros()" function.

So I have a C++ object:

class RunLoopItem
{

public:

RunLoopItem ( ) :
runTime ( 0 )
{

}

~RunLoopItem ()
{

}

void run ()
{
if ( 0>runTime )
reallyRun() ;
}

private:
virtual void reallyRun ()
{

}
UInt32 runTime ;

} ;

In the "run" method, if I replace "0" with "micros()", I get an error:

In member function 'void RunLoopItem::run()':

...And that's it... Anyone know why this is?

Some notes:
--> It compiles just fine with the "0" in place
--> "UInt32" is typedef'd to "unsigned long." I picked it up from programming with the CoreFoundation and like it because it's very clear...
--> NO "C" function will work when placed inside a C++ method... "malloc," which works in "loop" and "setup," does not work in the method, even though the method ".h" file is included within the same file as the "setup" and "loop" functions

2

First, note that "if (0>runTime)" is always true since runTime is an unsigned type thus could never be less than 0.

It compiles fine for me if I replace "UInt32" with "unsigned long".

It might be that you're including a header file which uses a namespace. Try replacing 'micros()' with '::micros()'.

3

I know 0>runTime is always true - I did that so that I'd know it would compile correctly...

I just tried the ::micros() and it didn't work... and I'm not using a namespace in the headers

This is weird. And annoying.

4

Just so everyone knows, here is the full extent of the code I have:

sketch_090526a:

#ifndef iRunLoopItem
#include "RunLoopItem.h"
#endif

#define numberOfItems 5
RunLoopItem * items[numberOfItems] ;

void setup ()
{
for ( int i=0 ; i<numberOfItems ; i++ )
{
items = 0 ;

  • }*

// items[0] = new RunLoopItemSUBCLASS ( ...params... ) ; <-- Example of what I'll do
}
void loop ()
{

}[/quote]
RunLoopItem.h:
> #ifndef iDefinitions
> #include "definitions.h"
> #endif
>
> #define iRunLoopItem
>
>
>
> class RunLoopItem
> {
*> *
> public:
*> *
> RunLoopItem ( ) :
> runTime ( 0 )
> {
*> *
> }
*> *
> ~RunLoopItem ()
> {
*> *
> }
*> *
*> *
> void run ()
> {
> run ( ::micros() ) ;
> }
> void run ( UInt32 inTime )
> {
> if ( inTime>runTime )
> reallyRun() ;
> }
*> *
> private:
> virtual void reallyRun ()
> {
*> *
> }
> UInt32 runTime ;
*> *
*> *
*> *
*> *
> } ;
definitions.h:
> #define iDefinitions
>
>
> typedef unsigned long UInt32 ;
In "RunLoopItem.h,"
This works:
> void run ()
> {
> run ( 0 ) ;
> }
This doesn't:
> void run ()
> {
> run ( ::micros() ) ;
> }
Nor does this:
> void run ()
> {
> run ( micros() ) ;
> }

5

You'll need to include the <WProgram.h> in your header that will use Arduino specific functions/datatypes. :slight_smile:

6

Thanks!

Is that written somewhere painfully obvious on the website, or do you just have to find out here on the forums?

7

Is that written somewhere painfully obvious on the website, or do you just have to find out here on the forums?

In short; no.

But here is:
http://arduino.cc/en/Hacking/LibraryTutorial
http://www.arduino.cc/playground/Code/Library

8

Has that <WProgram.h> requirement gone away in version 0015 of the tools? I swear his code compiled fine on my system without it.

9

Also, if you get error messages like that which seem to have the details missing, try turning on build.verbose in the preferences file--although you might also need to try to compile outside the IDE as I recall...

It seems the IDE has problems parsing some kinds of error messages.

--Phil.

10

Has that <WProgram.h> requirement gone away in version 0015 of the tools?

No.

I swear his code compiled fine on my system without it.

How many times in my life have I said that!

  • Brian
11

Ok... So now I need "malloc," which is in stdlib.h

So I included it... and it's still not working...

Is there anything stupid I should know about when it comes to avr-gcc?

12

Do you really need malloc? When you've only got 2048 (or 1024) bytes of ram, the overhead of using memory allocation is usually not worth it. I betcha you could do it without malloc() or new(). Can you show what you need it for?

-Paul

13

I don't get this little snippet:

runTime ( 0 )
 {
   
 }

That looks like a syntax error to me...?

Mikal

14 
runTime ( 0 )

{
 
}




That looks like a syntax error to me...?

It is the syntax for initializing a private member variable when constructing an object. :slight_smile:

Almost equivalent of:

{
   runTime = 0;
}
15

:slight_smile:

Ding dong! Didn't see the colon above. Thanks. Incidentally, that syntax is not restricted to private members, but you probably knew that.