prog20_06.cpp

一本语言类编程书籍

// Program 20.6 Taking the average of values from a string stream.
// File: prog20_06.cpp
#include <iostream>
#include <iterator> 
#include <string>
#include <sstream>              // For the istringstream class
using std::cout;
using std::endl;
using std::istream_iterator;
using std::istringstream;
using std::string;

template <typename Iter> 
double average(Iter begin, Iter end) { 
  double sum = 0.0;
  int count = 0;  
  for( ; begin != end ; ++count)
    sum += *begin++;
  return sum/(count == 0 ? 1 :count);   
} 

int main() {
 // char* stock_ticker = "4.5 6.75 8.25 7.5 5.75";
  std::string stock_ticker = "4.5 6.75 8.25 7.5 5.75";
  istringstream ticker(stock_ticker);
  istream_iterator<double> begin(ticker);
  istream_iterator<double> end;

  cout << "Readings: " << stock_ticker << endl 
       << "Today's average is "
       << average (begin, end) << endl; 
  return 0;
}