Question

I need to progressively build a string and am trying to find the best way to do it. The maximum it can grow to is about 10k and hence was planning to do something like this:

const unsigned long long configSize = 10240; //Approximation
void makeMyConfig() {
   std::string resp;
   std::string input;
   resp.reserve(configSize);
   while ( getInput(input) ) {
     resp += input;
   }

   if ( resp.length > configSize ) 
      log << "May need to adjust configSize. Validate" << endl;

   if (!sendConfig(resp)){
      log << "Error sending config" << endl;
   }
}

getInput may read from file/tcp conn or ftp and is decided at runtime. It receives const char* and puts it into a string (which I may be able to avoid but left it for convenience)

However, I heard there is a much efficient way of doing with string streams but not sure how to do. Appreciate any insights.

Answer 1

Looks pretty great to me.

• You’re pre-allocating the buffer, avoiding ongoing allocations and copies.
• You already have it implemented

Don’t optimize until you actually have a performance problem and can measure any performance changes. You might end up making it worse without realizing!