datascan.cpp

Think in C++ 第二版源码

//: C18:Datascan.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
//{L} Datalog
// Verify and view logged data
#include "DataLogger.h"
#include "../require.h"
#include <iostream>
#include <fstream>
#include <strstream>
#include <iomanip>
using namespace std;

int main() {
  ifstream bindata("data.bin", ios::binary);
  assure(bindata, "data.bin");
  // Create comparison file to verify data.txt:
  ofstream verify("data2.txt");
  assure(verify, "data2.txt");
  DataPoint d;
  while(bindata.read(
    (unsigned char*)&d, sizeof d))
    d.print(verify);
  bindata.clear(); // Reset state to "good"
  // Display user-selected records:
  int recnum = 0;
  // Left-align everything:
  cout.setf(ios::left, ios::adjustfield);
  // Fixed precision of 4 decimal places:
  cout.setf(ios::fixed, ios::floatfield);
  cout.precision(4);
  for(;;) {
    bindata.seekg(recnum* sizeof d, ios::beg);
    cout << "record " << recnum << endl;
    if(bindata.read(
      (unsigned char*)&d, sizeof d)) {
      cout << asctime(&(d.getTime()));
      cout << setw(11) << "Latitude"
           << setw(11) << "Longitude"
           << setw(10) << "Depth"
           << setw(12) << "Temperature"
           << endl;
      // Put a line after the description:
      cout << setfill('-') << setw(43) << '-'
           << setfill(' ') << endl;
      cout << setw(11) << d.getLatitude()
           << setw(11) << d.getLongitude()
           << setw(10) << d.getDepth()
           << setw(12) << d.getTemperature()
           << endl;
    } else {
      cout << "invalid record number" << endl;
      bindata.clear(); // Reset state to "good"
    }
    cout << endl
      << "enter record number, x to quit:";
    char buf[10];
    cin.getline(buf, 10);
    if(buf[0] == 'x') break;
    istrstream input(buf, 10);
    input >> recnum;
  }
} ///:~