C++函数模板示例2（配合decltype）

 #include "stdafx.h"

    
 #include <iostream>
    
 #include <iomanip>
    
 #include <string.h>
    
 #include <new>
    
  
    
 using std::cout;
    
 using std::cin;
    
 using std::endl;
    
 using std::setw;
    
  
    
 template<class T1, class T2> 
    
 auto product(T1 v1[], T2 v2[], size_t count) -> decltype(v1[0]*v2[0])
    
 {
    
 	decltype(v1[0]*v2[0]) sum(0);
    
 	for(size_t i=0;i<count;i++) sum += v1[i]*v2[i];
    
 	return sum;
    
 }
    
  
    
  
    
 int main(int argc,_TCHAR* argv[])
    
 {
    
 	double x[] = {100.5,99.5,88.7,77.8};
    
 	short y[] = {3,