extra line breaks from recv?

This is a discussion on extra line breaks from recv? within the C++ Programming forums, part of the General Programming Boards category; Extra line breaks appear to be added to my message that is generated from characters which are in turn passed ...

  1. #1
    Registered User xconspirisist's Avatar
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    extra line breaks from recv?

    Extra line breaks appear to be added to my message that is generated from characters which are in turn passed from recv(). It is fine for the first message, when you press enter for the first time, then the messages have characters seperated by these linebreaks. Ohwell, if anyone can help, i'd much appreciate, if you dont understand, please do say I i'll attempt to clarify.

    Code:
    void CConnectionManager::CheckNewMessages() {	
    	sUserSock * pUser = m_pUserList->pNext;
    
    	char character[MAX_CLIENT_MESSAGE_SIZE];
    	string message;
    
    	while (pUser != NULL) { // loop through users
    		memset(character, 0x0, MAX_CLIENT_MESSAGE_SIZE);
    		while (recv(pUser->sUser, character, sizeof(character), 0) > 0) {
    
    			printf( "ascii code: %i \n\r", (int)character[0] );
    
    
    			switch ((int)character[0]) {
    				case 13:
    					cout << "message: " << message << endl;
    					HandleMessage( message, pUser->nPlayerId );
    					message = "";
    					break;
    
    				default:
    					message += character;
    					cout << pUser->nPlayerId << " | message: " << message << endl;
    					break;
    
    			}
    
    		}
    
    		pUser = pUser->pNext;
    	}
    }

  2. #2
    carry on JaWiB's Avatar
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    Well for starters, I think you need to null terminate the data you receive:
    Code:
    int bytes_recv = recv(pUser->sUser, character, sizeof(character);
    character[bytes_recv]='\0';
    I'm not sure that will fix the problem though. It might help to see what your send code looks like
    "Think not but that I know these things; or think
    I know them not: not therefore am I short
    Of knowing what I ought."
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  3. #3
    Registered User xconspirisist's Avatar
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    With a couple of modifications to that code, it worked fine, many thanks

  4. #4
    and the hat of wrongness Salem's Avatar
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    > int bytes_recv = recv(pUser->sUser, character, sizeof(character);
    > character[bytes_recv]='\0';
    Except if recv actually fills the buffer, this results in writing outside the array bounds
    Also, check the result isn't negative either (an error from recv)

    int bytes_recv = recv(pUser->sUser, character, sizeof(character)-1) ;
    if ( bytes_recv > 0 ) character[bytes_recv]='\0';
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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