mean_procedure_auto.cpp

#include <iostream>

int main(){

  auto ncount=0,rsum=0,indata=0;
  auto amean=0.;
  decltype(rsum/ncount) truncmean;

  std::cout <<"Enter values [Ctrl-D to finish]: \n" ;
  while(std::cin>>indata){
    rsum+=indata; // rsum=rsum+indata;
    ncount++; // ncount=ncount+1;
    auto stemp=static_cast<double>(rsum);
    auto ntemp=static_cast<double>(ncount);
    amean=(ntemp!=0)?stemp/ntemp:0.;
    truncmean=(ntemp!=0)?rsum/ncount:0;
  }

  std::cout <<"Arithmetic mean: " << amean<< '\n';
  std::cout <<"Rounded to int mean: " << truncmean<< std::endl;
  return 0;
}