Thread: Problem with #import

Hi,

I'm trying to create a program, that can handle song requests. Trough a webpage, someone can request a song, that song will be stored in a MySQL Database.

With my C++ program I want to select the requests, and if there're some requests, I want my program to play the song.

To communicate with winamp, I use this winamp plugin:
http://mysite.wanadoo-members.co.uk/...ock/Winamp.htm

I took al look at the C++ examples, and found out, that he uses #import to import the plugin DLL, and than create an instance to communicate with winamp.

So, I have this code now:

request.h

Code:

#import "c:\program files\winamp\plugins\gen_com.dll"

// Create prototype from Request class
class Request
{
      public:
             Request();
             ~Request();
             
      protected:
             // Mysql vars
             MYSQL mysql;
             MYSQL_RES *result;
             MYSQL_ROW row;
             
             // Winamp vars
             WINAMPCOMLib::IApplicationPtr winamp;
             
             // Functions
             void handle_requests();
             
};

and

main.cpp

Code:

#include <mysql/mysql.h>
#include <cstdlib>
#include <iostream.h>
#include "request.h"

using namespace std;

Request::Request()
{
	// Create winamp instance
	winamp.CreateInstance(__uuidof(WINAMPCOMLib::Application));
	
	// Connect to DB and, select DB
	mysql_init(&mysql);
	
	if(!mysql_real_connect(&mysql, "localhost", "lucas", "charizard", "luckyradio"))
	{
		cout << "Failed to connect to database:\n" << mysql_error(&mysql);
		exit(1);
	}
}
Request::~Request()
{
	mysql_close(db_conn);
}

Request::handle_requests()
{
	cout << "Started Winamp Request Handler";
	while(true)
	{
		if(!winamp->CurrentPos)
		{
			// Ok, end of a song, check for requests
			if(mysql_query(&mysql, "SELECT * FROM e107_wa_requests ORDER BY request_id ASC LIMIT 1"))
			{
				result = mysql_store_result(&mysql);
				
				while(row = mysql_fetch_row(result))
				{
					cout << "Requesting " << winamp->SongTitle(row[1]) << "..."; 	
					winamp->PlayListPos = row['request_playlist_nr'];
					winamp->Play();
						
					mysql_query(&mysql, sprintf("DELETE FROM e107_wa_requests WHERE request_id = %d", row[0]));					
				}
			} 
					
				
		}
	}
}

int main(int argc, char *argv[])
{
	Request request;
	request.handle_requests();
    
	system("PAUSE");
	return EXIT_SUCCESS;
}

But when I try to compile it, I get a lot of errors like

Stray '\14' in program
Stray '\31' in program
etc

and

[Warning] Null charactar(s) ignored

I use Dev-C++, newest version.

Does anyone know how to fix this?

And, another question:

Is it possible to use vars in strings?
like in PHP:

Code:

$name = "Peter";
echo "Hello ".$name;

Does this also work in C++?
Like this?

Code:

mysql_query(&mysql, "DELETE FROM e107_wa_requests WHERE request_id = ".row[0]);

So much for MrLucky.

And, another question:

Is it possible to use vars in strings?
like in PHP:

Code:

$name = "Peter";
echo "Hello ".$name;

For C++ strings, you can use the + operator:

Code:

string name = "Peter";
name = name + " Lastname";

For C strings (character arrays), use strcat().

Code:

#include <cstring>
char name[100] = "Peter";

strcat(name, " Lastname");

And now for your first question. Evidently your compiler doesn't like this:

Code:

#import "c:\program files\winamp\plugins\gen_com.dll"

It seems to be functioning in the same way as #include. I would suggest linking your programs to the DLL instead. Create a project (if you haven't already) and add the DLL to the libraries to link to.

#import is a VC++-specific feature. You can't use it in Dev-C++. What it does is read COM type information from the DLL and automatically create a wrapper class. Without this feature, your code will be a lot more complicated.

Sure. Call CoInitialize, CoCreateInstance, QueryInterface, and all the other ridiculously complicated COM stuff.

I suggest you search for tutorials. It's mostly boilerplate code, so you don't even really need to understand it.