c++返回引用

#include <iostream>
#include <ctime>
 
using namespace std;
 
double vals[] = {10.1, 12.6, 33.1, 24.1, 50.0};
 
double[]& setValues( int i ) {
   return vals;   // return a reference to the ith element
}
 
// main function to call above defined function.
int main () {
 
   cout << "Value before change" << endl;
   for ( int i = ; i < ; i++ ) {
      cout << "vals[" << i << "] = ";
      cout << vals[i] << endl;
   }
 
   setValues()[] = 20.23; // change 2nd element
   setValues()[] = 70.8;  // change 4th element
 
   cout << "Value after change" << endl;
   for ( int i = ; i < ; i++ ) {
      cout << "vals[" << i << "] = ";
      cout << vals[i] << endl;
   }
   return ;
}