Probably a very simple problem - hopefully someone will help me

Probably a very simple problem - hopefully someone will help me

[David Ayliffe]

[-- Attachment #1: Type: text/plain, Size: 2107 bytes --]

Hello and thanks for your time.
I have been subscribed to this list now for 1824 posts but this is my
first post.
I have a file (attached) which I can't compile under cygwin using gcc.
Is it possible for this file to be compiled using cygwin, and if so can
you point me to where I am going wrong?  Sorry if this is a REALLY dolly
question but we all start somewhere.  PS This code compiles fine under
VC6.

I get these errors when I compile using the command directly below

$ gcc byte_hacking.cpp
byte_hacking.cpp: In function 'int main():
byte_hacking.cpp:20 implicit declaration of function 'int lseek(...)'
byte_hacking.cpp:22 implicit declaration of function 'int read(...)'
byte_hacking.cpp:27 implicit declaration of function 'int write(...)'
byte_hacking.cpp:25 implicit declaration of function 'int close(...)'

Thanks lots
David Ayliffe (mail@ayliffe.com)

Running Windows 2000 Advanced Server (SP2) with Cygwin gcc 2.95.3-5
Also running Suse Linux 7.1 Professional kernel 2.4








<ATTATCHED CODE FOR THOSE WHO CANT BE BOTHERED TO OPEN THE ATTACHMENT>
//Gets records from a MS Access Database

#include <io.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys\stat.h>

//#define database = northwind.mdb;

int main ()
{
	int f,buf;
	int isuccess = 0;

	printf ("Lists records in database\n");
	printf ("**************************\n\n");
	if (chmod("northwind.mdb",S_IWRITE)!=-1 && (f=open
("northwind.mdb",O_RDWR | O_BINARY))!=-1) 
	{
			 //handle, offest, origin

		if (lseek (f,0,SEEK_SET)!=1) 
		{
			if (read (f,&buf,2)==2 && buf==0x037D) 
			{
				printf ("Reading records");
				lseek (f,346345,SEEK_SET);
				buf=0x9090; //nop nop
				if (write(f,&buf,2)==2)  
				{	
					printf ("Success.");
				}
				else 
				{
					printf ("Failed due to unknown
reason.");
				}
			} 
			else 
			{			
				printf("Cannot find start location.
File may not be .mdb file");
			}
		} 
		else 
		{
			printf("Seek error.");
		}
		close(f);
    } 
	else 
	{
		printf ("Cannot find northwind.mdb");
	}
	return isuccess;
}

<END OF ATTATCHED CODE FOR THOSE WHO CANT BE BOTHERED TO OPEN THE
ATTACHMENT>

[-- Attachment #2: byte_hacking.cpp --]
[-- Type: text/x-c, Size: 964 bytes --]

//Gets records from a MS Access Database

#include <io.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys\stat.h>

#define database = northwind.mdb;

int main ()
{
	int f,buf;
	int isuccess = 0;

	printf ("Lists records in database\n");
	printf ("**************************\n\n");
	if (chmod("northwind.mdb",S_IWRITE)!=-1 && (f=open ("northwind.mdb",O_RDWR | O_BINARY))!=-1) 
	{
			 //handle, offest, origin				
		if (lseek (f,0,SEEK_SET)!=1) 
		{
			if (read (f,&buf,2)==2 && buf==0x037D) 
			{
				printf ("Reading records");
				lseek (f,346345,SEEK_SET);
				buf=0x9090; //nop nop
				if (write(f,&buf,2)==2)  
				{	
					printf ("Success.");
				}
				else 
				{
					printf ("Failed due to unknown reason.");
				}
			} 
			else 
			{			
				printf("Cannot find start location.  File may not be .mdb file");
			}
		} 
		else 
		{
			printf("Seek error.");
		}
		close(f);
    } 
	else 
	{
		printf ("Cannot find northwind.mdb");
	}
	return isuccess;
}

Re: Probably a very simple problem - hopefully someone will help me

[edward]

1. fix your #include (note incorrect backslash)

2. use gcc (and get rid of the c++ comments), or
   use g++ (and use the proper includes)

3. thanks for making me laugh =)

edward


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Re: Probably a very simple problem - hopefully someone will help me

[Kurt Roeckx]

On Sun, Jul 22, 2001 at 09:51:07PM +0100, David Ayliffe wrote:
> 
> I get these errors when I compile using the command directly below
> 
> $ gcc byte_hacking.cpp
> byte_hacking.cpp: In function 'int main():
> byte_hacking.cpp:20 implicit declaration of function 'int lseek(...)'
> byte_hacking.cpp:22 implicit declaration of function 'int read(...)'
> byte_hacking.cpp:27 implicit declaration of function 'int write(...)'
> byte_hacking.cpp:25 implicit declaration of function 'int close(...)'

They're not errors, they're warnings.

> //Gets records from a MS Access Database
> 
> #include <io.h>
> #include <fcntl.h>
> #include <stdio.h>
> #include <sys\stat.h>

It should be <sys/stat.h>, and you forgot: #include <unistd.h>
which declares all of those functions.


Kurt


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Re: Probably a very simple problem - hopefully someone will help me

[Kurt Roeckx]

On Mon, Jul 23, 2001 at 11:44:59PM +0200, Heribert Dahms wrote:
> 
> almost! According to Appendix A of Richard W. Steven's famous
> "Advanced Programming in the UNIX Environment" (a "must have" IMHO)
> lseek needs including <sys/types.h> before <unistd.h>!

And so do things like open() if you look at certain manpages.
Not all manpages mention it, and not all libc need them.  That
doesn't mean you shouldn't include it however. :)

But gcc only complained about the missing declarations for the
functions, and I knew that all those functions had unistd.h in
common.

I wonder where the manpages for "system calls" are under cygwin.
Section two is completly missing.


Kurt


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RE: Probably a very simple problem - hopefully someone will help me

[Heribert Dahms]

Hi Kurt,

almost! According to Appendix A of Richard W. Steven's famous
"Advanced Programming in the UNIX Environment" (a "must have" IMHO)
lseek needs including <sys/types.h> before <unistd.h>!

Bye, Heribert (heribert_dahms@icon-gmbh.de)

> -----Original Message-----
> From:	Kurt Roeckx [SMTP:Q@ping.be]
> Sent:	Monday, July 23, 2001 17:23
> To:	cygwin@cygwin.com
> Cc:	cygwin@cygwin.com
> Subject:	Re: Probably a very simple problem - hopefully someone will
> help me
> 
> On Sun, Jul 22, 2001 at 09:51:07PM +0100, David Ayliffe wrote:
> > 
> > I get these errors when I compile using the command directly below
> > 
> > $ gcc byte_hacking.cpp
> > byte_hacking.cpp: In function 'int main():
> > byte_hacking.cpp:20 implicit declaration of function 'int lseek(...)'
> > byte_hacking.cpp:22 implicit declaration of function 'int read(...)'
> > byte_hacking.cpp:27 implicit declaration of function 'int write(...)'
> > byte_hacking.cpp:25 implicit declaration of function 'int close(...)'
> 
> They're not errors, they're warnings.
> 
> > //Gets records from a MS Access Database
> > 
> > #include <io.h>
> > #include <fcntl.h>
> > #include <stdio.h>
> > #include <sys\stat.h>
> 
> It should be <sys/stat.h>, and you forgot: #include <unistd.h>
> which declares all of those functions.
> 
> 
> Kurt
> 
> 
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