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Old 12-09-2005, 01:37 AM   #1
lucky6969b
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scope of an object and global scope


I've got a var. defined as
int fd; globally available throughout my application
in a global include file say #include "myapp.h"

I've got another class which resides on another file
lets say #include "serialport.h"
this class has

serialport:pen()
{
fd = open (....);
}

Return to the globol scope
I've got a non-class reference to fd available which always appears to be 0. Does the scope present an issue?
Thanks
Jack
 
Old 12-09-2005, 07:46 AM   #2
dmail
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so the variable is not defined as static then?
try including the following in "serialport.h" and see if that makes a difference.
Code:
extern int fd;
 
Old 12-09-2005, 08:13 PM   #3
lucky6969b
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Still zero. I actually opened the fileHandle with
#include "myapp.h"
extern int fd;
void CSerialPort::Open ()
{
fd = open(...)
}
//////////////////////////////////////////////
and access it this way
extern int fd
#include "myapp.h"
void PortMonitorThread(void)
{
read (fd..)
}

where fd is declared above all cpp files
so
in myapp.h
static int fd;

Thanks
Jack
 
Old 12-09-2005, 08:14 PM   #4
lucky6969b
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Typing mistakes. But they compiled okay
 
Old 12-09-2005, 08:39 PM   #5
lucky6969b
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The Callback function was invoked by a thread. Does it pose any problems?
Jack
 
Old 12-09-2005, 08:40 PM   #6
lucky6969b
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PortMonitorThread exactly
 
Old 12-09-2005, 08:50 PM   #7
lucky6969b
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Still zero. I actually opened the fileHandle with
#include "myapp.h"
extern int fd;
void CSerialPort::Open ()
{
fd = open(...)
}
//////////////////////////////////////////////
and access it this way
extern int fd
#include "myapp.h"
void PortMonitorThread(void)
{
read (fd..)
}

where fd is declared above all cpp files
so
in myapp.h
static int fd;

Thanks
Jack
 
Old 12-09-2005, 09:09 PM   #8
lucky6969b
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It's got to be some C versus C++ scope problems. But I don't know where to look and start. Any hints?
Thanks
Jack
 
  


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