C++对象、继承和引用

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#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
void file_it(ostream &os,double fo,const double fe[],int n);
const int Limit=5;
int main()
{
ofstream fout;
const char *fn="ep-data.txt";
fout.open(fn);
if(!fout.is_open())
{
cout << "Can't open " << fn << ". Bye.n";
exit(EXIT_FAILURE);
}
double objective;
cout << "Enter the focal lenth of your telescope objective in mm: ";
cin >> objective;
double eps[Limit];
cout << "Enter the focal lenths, in mm, of " << Limit << " eyepieces.n";
for(int i=0; i<Limit; i++){
cout << "Eyepiece #" << i+1 << ": ";
cin >>eps[i];
}
file_it(fout,objective,eps,Limit);
file_it(cout,objective,eps,Limit);
cout << "Done.n";
return 0;
}
void file_it(ostream &os,double fo,const double fe[],int n)
{
ios_base::fmtflags initial;
initial=os.setf(ios_base::fixed);
os.precision(0);
os << "Focal lenth of objective: " << fo << " mmn";
os.setf(ios::showpoint);
os.precision(1);
os.width(12);
os << "f.1 eyepiece";
os.width(15);
os << "magnification" << endl;
for(int i=0; i<n; i++){
os.width(12);
os << fe[i];
os.width(15);
os << int(fo/fe[i]+0.5) << endl;
}
os.setf(initial);
}

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Enter the focal lenth of your telescope objective in mm: 1800
Enter the focal lenths, in mm, of 5 eyepieces.
Eyepiece #1: 30
Eyepiece #2: 19
Eyepiece #3: 14
Eyepiece #4: 8.8
Eyepiece #5: 7.5
Focal lenth of objective: 1800 mm
f.1 eyepiece
magnification
30.0
60
19.0
95
14.0
129
8.8
205
7.5
240
Done.