Recv returning zero incorrectly [closed]

问题

I have an interesting problem,

I send bytes of data to my server, from my client, and the recv() function always returns zero.
I have verified that the function is indeed getting the data and placing it into the char array correctly. It just returns zero regardless of the number of bytes received.
I have verified that the client is still properly connected after recv() returns a zero, and can still send and receive data to and from the server.

This creates a problem for me. I need to total up the chars coming in to determine when a message is completed. Can someone explain what could cause the recv() command to behave in this manner?

// clean the buffer of any previous received data
// by resetting all bytes to zero
ReadBufferClear();

// try to read some data, using the read buffer
if(this->Return_Value = recv(this->Socket_Filedescriptor,            
                    this->ReadBuffer_Data,
                    this->ReadBuffer_Size,
                    0) == -1)
{
    // returned -1, notify the server it needs
    // to remove this connections FD, and 
    // close this connection class entry;
    return -1;
}    

// print return value
fprintf(stdout,"%i\n",this->Return_Value);

// print out the bytes
for(int curPos  =0; curPos<this->ReadBuffer_Size; curPos++)
    fprintf(stdout,"%i\n",this->ReadBuffer_Data[curPos]);

output looks like this:

0 0 1 -1 -1 -1 -2 -1 -1 0 0

回答1:

You have a precedence problem. The line should be of the form

if ((this->ReturnValue = recv(..).)) == -1)

At present you're comparing the result of recv() with -1 and storing the Boolean result of that comparison into ReturnValue.

So recv() isn't returning zero at all.

来源：https://stackoverflow.com/questions/23866637/recv-returning-zero-incorrectly

标签

c++

networking

recv