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#include <iostream>
#include <algorithm>
#include <fstream>
#include <sparsepp/spp.h>
using spp::sparse_hash_map;
using namespace std;
struct StringToIntSerializer
{
bool operator()(std::ofstream* stream, const std::pair<const std::string, int>& value) const
{
size_t sizeSecond = sizeof(value.second);
size_t sizeFirst = value.first.size();
stream->write((char*)&sizeFirst, sizeof(sizeFirst));
stream->write(value.first.c_str(), sizeFirst);
stream->write((char*)&value.second, sizeSecond);
return true;
}
bool operator()(std::ifstream* istream, std::pair<const std::string, int>* value) const
{
// Read key
size_t size = 0;
istream->read((char*)&size, sizeof(size));
char * first = new char[size];
istream->read(first, size);
new (const_cast<string *>(&value->first)) string(first, size);
// Read value
istream->read((char *)&value->second, sizeof(value->second));
return true;
}
};
int main(int , char* [])
{
sparse_hash_map<string, int> users;
users["John"] = 12345;
users["Bob"] = 553;
users["Alice"] = 82200;
// Write users to file "data.dat"
// ------------------------------
std::ofstream* stream = new std::ofstream("data.dat",
std::ios::out | std::ios::trunc | std::ios::binary);
users.serialize(StringToIntSerializer(), stream);
stream->close();
delete stream;
// Read from file "data.dat" into users2
// -------------------------------------
sparse_hash_map<string, int> users2;
std::ifstream* istream = new std::ifstream("data.dat");
users2.unserialize(StringToIntSerializer(), istream);
istream->close();
delete istream;
for (sparse_hash_map<string, int>::iterator it = users2.begin(); it != users2.end(); ++it)
printf("users2: %s -> %d\n", it->first.c_str(), it->second);
}