1 // endian/example/conversion_use_case.cpp
2
3 // Copyright Beman Dawes 2014
4
5 // Distributed under the Boost Software License, Version 1.0.
6 // See http://www.boost.org/LICENSE_1_0.txt
7
8 // This program reads a binary file of fixed length records, with a format defined
9 // in a header file supplied by a third-party. The records inserted into a vector,
10 // and the vector is sorted. The sorted records are then written to an output file.
11
12 // Full I/O error testing omitted for brevity, So don't try this at home.
13
14 #include "third_party_format.hpp"
15 #include <boost/endian/conversion.hpp>
16 #include <vector>
17 #include <fstream>
18 #include <algorithm>
19 #include <iostream>
20
21 using third_party::record;
22
main()23 int main()
24 {
25 std::ifstream in("data.bin", std::ios::binary);
26 if (!in) { std::cout << "Could not open data.bin\n"; return 1; }
27
28 std::ofstream out("sorted-data.bin", std::ios::binary);
29 if (!out) { std::cout << "Could not open sorted-data.bin\n"; return 1; }
30
31 record rec;
32 std::vector<record> recs;
33
34 while (!in.eof()) // read each record
35 {
36 in.read((char*)&rec, sizeof(rec));
37 rec.balance = boost::endian::big_to_native(rec.balance); // reverse if needed
38 recs.push_back(rec);
39 }
40
41 std::sort(recs.begin(), recs.end(), // decending sort by balance
42 [](const record& lhs, const record& rhs) -> bool
43 { return lhs.balance > rhs.balance; });
44
45 for (auto &out_rec : recs) // write each record
46 {
47 out_rec.balance = boost::endian::native_to_big(out_rec.balance); // reverse if needed
48 out.write((const char*)&out_rec, sizeof(out_rec));
49 }
50
51 }
52