datascan.cpp

来自「Think in C++文中代码实现」· C++ 代码 · 共 90 行

// File from page 266 in "Thinking in C++" by Bruce Eckel
//////////////////////////////////////////////////
// From the compressed package ECKELT02.ZIP 4/11/95
// (Original ECKELT01.ZIP dated 2/21/95)
// Copyright (c) Bruce Eckel, 1995 
// Source code file from the book "Thinking in C++", 
// Prentice Hall, 1995, ISBN: 0-13-917709-4
// All rights reserved EXCEPT as allowed by the following 
// statements: You may freely use this file for your own 
// work, including modifications and distribution in 
// executable form only. You may copy and distribute this 
// file, as long as it is only distributed in the complete 
// (compressed) package with the other files from this 
// book and you do not remove this copyright and notice. 
// You may not distribute modified versions of the source 
// code in this package. This package may be freely placed 
// on bulletin boards, internet nodes, shareware disks and 
// product vendor disks. You may not use this file in 
// printed media without the express permission of the 
// author. Bruce Eckel makes no 
// representation about the suitability of this software 
// for any purpose. It is provided "as is" without express 
// or implied warranty of any kind. The entire risk as to 
// the quality and performance of the software is with 
// you. Should the software prove defective, you assume 
// the cost of all necessary servicing, repair, or 
// correction. 
// If you think you've found an error, please 
// email all modified files with loudly commented changes 
// to: [e-mail] (please use the same 
// address for non-code errors found in the book).
//////////////////////////////////////////////////

//: DATASCAN.CPP -- Verify and view logged data
#include <fstream.h>
#include <strstrea.h>
#include <iomanip.h>
#include <assert.h>
#include "..\5\datalog.h"

main() {
  ifstream bindata("data.bin", ios::binary);
  assert(bindata); // Make sure it exists
  // Create comparison file to verify data.txt:
  ofstream 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.Time()));
      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.latitude()
           << setw(11) << d.longitude()
           << setw(10) << d.depth()
           << setw(12) << d.temperature()
           << 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;
  }
}