Re: Pointers to classes

[LDB <thesource@ldb-jab.org>]

Abstract class .........


LDB

John T. Williams wrote:

>Sorry wrong terminology. its not prototyping, but I can't remember what
>you call it when you give a partial class, i.e.
>class SomeClass;
>
>rather then full class
>
>class SomeClass {
>private:
>...
>public:
>...
>};
>
>?Maybe forward declaration ?  
>
>
>
>On Sun, 2004-06-20 at 01:06, John T. Williams wrote:
>  
>
>>Hello,   
>>
>>I'm only taking a stab here, to be sure I'd have to see the complete
>>file and #include's but it looks like your trying to use ConfigFile type
>>before you define it or prototype it.  If you define class ConfigFile
>>somewhere else then you can probably fix the error by adding the line 
>>
>>class ConfigFile;  
>>
>>before you try to define 
>>
>>class Connection { 
>>...
>>};  
>>
>>you might also want to add the lines
>>
>>#ifndef CONNECT_H
>>#define CONNECT_H
>>
>>to the very top of connect.h
>>
>>and 
>>
>>#endif
>>
>>to the very bottom of connect.h
>>
>>and do the same thing for every .h file you create.  This can save you
>>many many problems later  It helps to prevent accidental infinite
>>includes and other common problems.  
>>
>>Just to sum up my revised version of you connection.h
>>
>>---------------------start connection.h
>>#ifndef CONNECTION_H
>>#define CONNECTION_H
>>
>>class ConfigFile;
>>
>>class Connection
>>{
>>private:
>>...
>>ConfigFile* config;
>>...
>>public:
>>...
>>ConfigFile* getConfig();
>>};
>>
>>#endif
>>---------------------end connection.h
>>
>>
>>
>>On Sun, 2004-06-20 at 00:46, Eric wrote:
>>    
>>
>>>Hello
>>>	First I would like to say im fairly new to C++ and keep in mind you will 
>>>probably see many glaring mistakes in reading my code, please be kind. Hey, 
>>>thats how we learn :)
>>>
>>>	My problem is with pointers to classes. I am writing a VPN management program 
>>>and have a class Connection, which handles a connection ppp0, ppp1, etc, and 
>>>is closely tied with a class ConfigFile, which handles all the variables for 
>>>that connection obviously read from a file.
>>>
>>>	I need to have a pointer to an object ConfigFile inside the Connection class 
>>>so I can access variables and such associated with that connection that were 
>>>read from a file. However, I am getting very strange compile errors when 
>>>trying to define the pointer to a class. These are the errors. Below are the 
>>>relevant files and how they are included.
>>>
>>>*/home/bot403/programming/projects/vpn_client/src/connection.h:28: error: 
>>>syntax error before `*' token 
>>>*/home/bot403/programming/projects/vpn_client/src/connection.h:31: error: 
>>>parse error before `*' token 
>>>*/home/bot403/programming/projects/vpn_client/src/connection.h:36: error: 
>>>syntax error before `*' token
>>>
>>>
>>>Here are the relevant files. Please let me know if you need additional 
>>>information. 
>>>
>>>BTW, I don't consider making Connection a sublass of configfile a solution 
>>>becuase I am already teaching myself alot with this project and am happy with 
>>>simpleton solutions. Subclasses/Inheritance  would require that I teach 
>>>myself way too much to accomplish way too little.
>>>
>>>
>>>---------------------start connection.h
>>>class Connection
>>>{
>>>private:
>>>  char ifName[ 5 ];
>>>  char pppdopts[256];
>>>  char sshopts[256];
>>>  char pidfile[256];
>>>  ConfigFile * config;
>>>  pid_t pid;
>>>public:
>>>  Connection(ConfigFile * cFile );
>>>  void printName( void );
>>>  int start();
>>>  int stop();
>>>  ~Connection();
>>>  ConfigFile * getConfig();
>>>
>>>};
>>>----------------------- end file
>>>-----------------------start configfile.h
>>>int readElement( char buffer[], char option[], char argument[] );
>>>
>>>using namespace std;
>>>
>>>class ConfigFile {
>>> private:
>>>  ifstream configFile;
>>>  char configFileName[ 256 ];
>>>
>>>  //File variables
>>>  char pppdevice[ 8 ];
>>>  char vpnhost[ 256 ];
>>>  char logfile[ 256 ];
>>>  char *pppdopts;
>>>  //SSH Specific
>>>  char sshcipher[ 15 ];
>>>  char sshlogin[ 256 ];
>>>  char sshidentity[ 256 ];
>>>  char *sshopts;
>>>  char sshport[ 10 ];
>>>  //Misc
>>>  char delay[ 10 ];
>>>  char vpnpidfile[80];
>>>  //Connection Details
>>>  char *networks[5];
>>>  char *nameservers[2];
>>>  //End File Variables
>>>
>>> public:
>>>  ConfigFile( char *Name );
>>>  ~ConfigFile();
>>>  int readConfig();
>>>  void printConfig();
>>>  int writeConfig(char *Filename);
>>>  
>>>  char *getsshopts(char buffer[]);
>>>  char *getpppdopts(char buffer[]);
>>>  char *getlogfile(char buffer[]);
>>>  char *getpidfile(char buffer[]);
>>>  
>>>  //FIXME
>>>  //char *getnetworks();
>>>  //char *getnameservers();
>>>  
>>>
>>>};
>>>
>>>-----------end of file
>>>-----------top of connection.cpp
>>>
>>>#include <iostream>
>>>#include <fstream>
>>>#include <unistd.h>
>>>#include "configfile.h"
>>>#include "connection.h"
>>>#include "strings.h"
>>>#include "config.h"
>>>------snip---------
>>>
>>>-----------------end file
>>>
>>>----------------top of configfile.cpp
>>>
>>>#include <iostream>
>>>#include <fstream>
>>>#include "configfile.h"
>>>#include "strings.h"
>>>-----snip------------
>>>
>>>--------------end of file
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>>>
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>>
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