1. ostream类中的格式化方法
// 8.8 filefunc.cpp -- function with ostream & parameter
#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 length of your telescope objective in mm: ";
cin >> objective;
double eps[LIMIT];
cout << "Enter the focal lengths, in mm, of " << LIMIT << " eyepieces: \n";
for (int i = 0; i < LIMIT; i++) {
cout << "Eyepieces #" << i + 1 << ": ";
cin >> eps[i];
}
file_it(fout, objective, eps, LIMIT);
file_it(