Sending and receiving std::string over socket

Question

I have seen similar question on SO but non answers my question. Here I am trying to send and recv string:

I am sending std::string :

if( (bytecount=         


        

Answer 1

The best way is to send the length of the string data first in a fixed format (e.g. a uint32_t in network byte order). Then the receiver can read this first and allocate a buffer of the appropriate size before receiving the serialized message that is send afterwards.

sd and csd are assumed to be already present socket descriptors.

Sender.cpp

std::string dataToSend = "Hello World! This is a string of any length ...";

uint32_t dataLength = htonl(dataToSend.size()); // Ensure network byte order 
                                                // when sending the data length

send(sd,&dataLength ,sizeof(uint32_t) ,MSG_CONFIRM); // Send the data length
send(sd,dataToSend.c_str(),dataToSend.size(),MSG_CONFIRM); // Send the string 
                                                           // data 

Receiver.cpp

uint32_t dataLength;
recv(csd,&rcvDataLength,sizeof(uint32_t),0); // Receive the message length
dataLength = ntohl(dataLength ); // Ensure host system byte order

std::vector rcvBuf;    // Allocate a receive buffer
rcvBuf.resize(dataLength,0x00); // with the necessary size

recv(csd,&(rcvBuf[0]),dataLength,0); // Receive the string data

std::string receivedString;                        // assign buffered data to a 
receivedString.assign(&(rcvBuf[0]),rcvBuf.size()); // string

Advantage is. you don't have to mess around with multiple buffered reads and copying to the received string. Additionally you'll know at the receiver side when the sent data is finally complete.

Disadvantage is, you're introducing kind of a 'protocol' when sending the length first.