Client-server program help

eric_tran

Gday everyone, I'd like to display recent received messages in the buffer 'msg_cat' when user types in 'display', but it always displays 'No recent messages' after I concatenated messages into 'msg_cat'. I use global buffer 'msg_cat'. Is there something wrong of the way I use 'msg_cat'? Or the affect of using fork function in main? I spent so much time on time, but I really don't know how to fix this problem. It really depends on you guys experts here. Please help me out if you're interested in this. I'd appreciate it.

char msg_cat[1000];

//Receive, store and display recent messages when user type 'display'.
void displayMulticastedMessage(int condition){
char *msg;
int stop = -1;

    //Display recent multicast messages.
if (condition == 2){
	if (strcmp(msg\_cat, "") != 0){
		printf("msg\_cat: %s", msg\_cat);
		strcpy(msg\_cat, "");
	}
	else{
		printf("No recent messages\\n");
	}
}

while(stop < 0){
	//Receive multicasted messages from server and store in msg buffer.
	msg = (char \*)recvfromDST (&read\_EP, sockMulti);	

	//Concatenate message msg into buffer msg\_cat.
	strcat(msg\_cat, msg);
	strcat(msg\_cat, "\\n");					

	//Display a receiving multicast message to user
	if (msg != NULL){
		printf("----- Waiting for Multicasted message ----- \\n");
		printf("\\nReceived multicast message ==> %s \\n", msg);
	}
	else{
		stop = 0;
	}			
}

}

void receiveUserMessage(int sock){
int stop = -1;
char *msg;

while (stop < 0){
	printf("Type message or 'display' to display recent multicasted messages or	'end' to quit \\n");	
	
	//Read msg from user
  		scanf ("%s", KB\_buff);		
	//Display recent multicast messages.
	if (strncmp(KB\_buff, "display", 7) == 0){	
		int display = 2;
		displayMulticastedMessage(display);
	}	
	
	//Check message format and send message if it is correct.
	else{			
			int stop = sentMessage(KB\_buff,sock);			
	}		
	printf("\\n");
}

}

int main(){

if (pid == 0) // i am the child process
{

		//Receive user input and commands
		receiveUserMessage(MC\_socket);
	}
	else 
	{
		if (pid < 0) // ERROR !
		{
			perror("fork");
			exit(1);
		}
		else // parent process
		{				
			int user = -1;
			displayMulticastedMessage(user);	
					
		}
	}

}

eric