I want to save this struct and load it later:
struct Block
{
vector<int> numbers;
map<int , char> bits;
map<string , string > states;
string off;
}relationTable[7][11][13];
Is there any way except use of several for loops ?
I use this function for save:
void saveData()
{
string location = "test.bin";
ofstream fs(location, std::ios::out | std::ios::binary | std::ios::app);
fs.write(reinterpret_cast<const char *>(relationTable), sizeof(relationTable));
fs.close();
}
And this one for load:
void loadData()
{
string location = "test.bin";
Block array[64][96][2];
ifstream file (location, ios::in|ios::binary|ios::ate);
if (file.is_open())
{
file.seekg (0, ios::beg);
file.read ((char*)&array, sizeof(array));
file.close();
}
...//some use of array
}
But it didn’t work, because it only save the pointers! What should i do?
Answer
It’s not very clear what is relationTable for you. If you want to save your structure into a file, the easier way is to use boost::serialization see : How do you serialize an object in C++?
you can do something like this :
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/map.hpp>
include <boost/serialization/string.hpp>
#include <boost/serialization/vector.hpp>
namespace boost {
namespace serialization {
template<class Archive>
void serialize(Archive & ar, Block& b, const unsigned int version)
{
ar & b.numbers;
ar & b.bits;
ar & b.states;
ar & b.off;
}
void save_Block(const Block &b, const char * filename){
// make an archive
std::ofstream ofs(filename);
boost::archive::text_oarchive oa(ofs);
oa << b;
}
}}
Fully working sample program:
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/map.hpp>
#include <boost/serialization/string.hpp>
#include <boost/serialization/vector.hpp>
#include <fstream>
struct Block
{
typedef std::vector<int> Numbers;
typedef std::map<int, char> Bits;
typedef std::map<std::string, std::string> States;
Numbers numbers;
Bits bits;
States states;
std::string off;
};
namespace boost { namespace serialization {
template<class Archive>
void serialize(Archive & ar, Block& b, const unsigned int version)
{
ar & b.numbers;
ar & b.bits;
ar & b.states;
ar & b.off;
}
} }
void save_Block(const Block &b, const char * filename){
// make an archive
std::ofstream ofs(filename);
boost::archive::text_oarchive oa(ofs);
oa << b;
}
int main()
{
save_Block(Block {
{ 1, -42 },
{ { 3, '0' }, { 17, '1' } },
{ { "disabled", "true" }, { "locked", "false" }, { "ui", "manual" } },
"something called 'off'"
},
"test.txt");
}
The file test.txt will contain:
22 serialization::archive 10 0 0 2 0 1 -42 0 0 2 0 0 0 3 48 17 49 0 0 3 0 0 0 8 disabled 4 true 6 locked 5 false 2 ui 6 manual 22 something called 'off'