SFML2 Split Packets and Cut Strings

[NorthernGate]

I have my Server and Client. My issue is that when I send a message through my client to my server the server receives it as chunks and if the word was longer than 4 characters it expunges any characters past the fourth and if it's 4 or greater it appends a set of funky symbols to the end of each packet.

Screens:

Client


Server

[Laurent]

Just a guess, which is the best I can do without seeing your code: maybe you send sizeof(some_ptr), which is always 4, instead of the actual number of bytes pointed by your pointer?

[NorthernGate]

That might be it, this is the function I'm using for my Send function.

Code: [Select]

void Client::Send( const char message[] )
{
if( Socket.Send( message, sizeof( message ), ConnectedTo.Address, ConnectedTo.Port ) != sf::Socket::Done )
Debug( "Network", "Error sending Packet" );
else Debug( "Network", "Message Sent" );
}

Here's my Servers Receive Function

Code: [Select]

void Server::Listen( void )
{
if( Socket.Receive( Data, sizeof( Data ), Received, Sender, Port ) != sf::Socket::Done )
Debug( "Network", "Error receiving Packet" );
else printf( "%s \"%s\"\n", Sender.ToString().c_str(), Data );
}

But if I'm not mistaken that code is near identical to what you used in the SDK Sample, including the sizeof parameter.

[Laurent]

Nop, it's not identical. It's tricky because the type of the data looks like the same (const char[]), but in fact it is not: when declaring an argument of type T[], in fact it is a T*, the compiler looses the size information. So sizeof(message) is always 4 in your function, you have to manage the size explicitely.

[NorthernGate]

Thanks, I managed to get the proper length of the array. But now I'm coming up with a separate problem, in my classes I have a 'char Data[]' variable. And after I send my first message or define a default value for Data I can't send any data larger than the first string I sent, or at least the server refuses to take it. I assume this is because char Data[] defines it's max length based on it's first value ( I jumped right into std::string when I learned C++ so I'm a bit ignorant on this sort of thing. ) So I made the char *Data instead, but this causes a crash during run-time, and my debugger ( as unreliable as it may be ) tells me it occurs on the line the Client's Send Function is called. This may be a bit off the side from any actual SFML business, but I was wondering what sort of string I should be passing to sf::UdpSocket::Send, the prototype says const char *, but as seen before that doesn't make my Server too happy.

[Laurent]

But now I'm coming up with a separate problem, in my classes I have a 'char Data[]' variable.

Same thing as before: it's in fact a char*, and you need to allocate memory for it. You should avoir using this array notation (with no explicit size), it's confusing because most of the time it's just a pointer, and it doesn't behave like an array with explicit size. Use std::vector if you want a dynamic array.

I was wondering what sort of string I should be passing to sf::UdpSocket::Send, the prototype says const char *

You can pass anything, here char* doesn't mean "string", it means "a sequence of bytes". So the input type doesn't really matter, you can simply reinterpret_cast it to const char*.

[NorthernGate]

Thanks, I think I'm going to stick to std::string from now on. Character arrays are really not my thing apparently. I haven't gotten the chance to cast yet, but I'm sure it'll work, thanks for your time.

[Tank]

And please, as a sidenote, check your "debugging words" before posting such screenshots to a public forum. There might be groups of people who won't be very happy to read something that begins with "Nigg...".