Question

I’m working on a UDP based file-sharing program. Let me post some sample code before explain the problem.

while (true) 
{
    Data toRecv;
    int bytesRead = recvfrom(s->_UPDsock, (char*)&toRecv, sizeof(toRecv), 0,(SOCKADDR*)&remoteAddress, &remoteAddresslength);
    if(bytesRead > 0)
    {
        string temp(toRecv.chunk,(bytesRead-sizeof(int)));
        if(!checker)
        {
            //total packet amount.
            totalChunkAmount = toRecv.ACK;
            checker = true;
        }
    }
}

As you can see at line “13” I’m initializing the totalChunkAmount by using the variable I got from UDP’s recvFrom function. I need to initialize that value only ONCE, that’s why I’m using it inside a bool if() check. and after the initialization, I’m flipping the bool value to true, so it will not be initialized again. Is there any other way to achieve the same result, but not using the ugly bool switching method.

Answer 1

Set totalChunkAmount to an invalid state before it’s initialized and check for that state. For example if totalChunkAmount is an int then,

totalChunkAmount = -1; // say -1 is invalid value
while(true)
{
 ...
 if(-1 == totalChunkAmount)
   totalChunkAmount = toRecv.ACK; // ACK can never be -1
}

Likewise, if totalChunkAmount is a pointer then you may set it to NULL (0).

[Edit Note: I am just wondering, in your while loop mainly you are initializing variable then why don’t your break out of the loop after that ? If you can do so it’s lot more cleaner and no such checks are needed.]