Small heaps of code

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====== Loops ======
===== Loop over a Sequence =====
<code cpp>
#include <boost/foreach.hpp> vector<string> ids; 

BOOST_FOREACH(string id, ids) {

// do something with id

}
</code>

===== Loop over a Mapping =====
<code cpp>
#include <boost/foreach.hpp> 
#include <boost/tuple/tuple.hpp> 

std::map<int, std::string> theMap;  
int key;  
std::string value;  

BOOST_FOREACH(boost::tuples::tie(key, value), theMap) {

std::cout << key << " => " << value << "\n";

}
</code>

====== Strings ======
===== Split a string =====
<code cpp>
#include <boost/algorithm/string.hpp>
vector<string> splitResult;
boost::split(splitResult,"wir;funktionieren;automatik;;",boost::is_any_of(";,.")); // results in |wir|funktionieren|automatik|
</code>

Note Boost's split behaviour where two separators meet in a string: split creates an empty element to signal there's no data between those two separators. Thus it's possible to reconstruct the original string.

===== Join a vector of strings =====
<code cpp>
#include <boost/algorithm/string.hpp> 

vector<string> data_bits; 
string data_copy = boost::join(data_bits,",");
</code>

===== Lexical cast =====
<code  cpp>
#include <boost/lexical_cast.hpp> int i = boost::lexical_cast<int>("2");
</code>

====== Filesystem ======
===== Finding a file =====
[[http://www.boost.org/doc/libs/1_35_0/libs/filesystem/doc/index.htm TODO]]

====== Containers ======
===== STL-Vector =====
==== Append vector to other vector ====
<code cpp>
vector<int> a,b;
a.insert(a.end(),b.begin(),b.end());
</code>

===== BOOST-List/map hybrid =====
Sometimes a container with fast access possibilities AND insertion order preserving capability is needed. Boost's multi_index_container helps (see [[http://docs.huihoo.com/boost/1-33-1/libs/multi_index/doc/tutorial.html#seq_indices here for more]]): Use a sequenced index together with oder indizes of your choice.

==== Example: creating a lookup table for flags and full names ====
f -> fleetid

t -> timestamp...

<code cpp>
#include <boost/multi_index_container.hpp>
#include <boost/multi_index/member.hpp>
#include <boost/multi_index/sequenced_index.hpp>
#include <boost/multi_index/ordered_index.hpp>

namespace bmi = boost::multi_index;

struct FlagInfo {
    std::string flag;       // eg. F
    std::string full_name;  // eg. fleetid

    FlagInfo(std::string f,std::string n):flag(f),full_name(n) {}
 };

struct flag{}; // to access the tag

/** a map/list hybridcontainer preserving insertion order and indexing by flag*/
typedef bmi::multi_index_container<
    FlagInfo,
    bmi::indexed_by<
        bmi::sequenced<>,
        bmi::ordered_unique< bmi::tag<flag>,  BOOST_MULTI_INDEX_MEMBER(FlagInfo,std::string,flag)>
  >
 > FlagList;
// map/list-like container

typedef FlagList::iterator FlagListIterator;
</code>

==== Insert some elements ====
<code cpp>
FlagList flag_list;
flag_list.get<1>().insert(FlagInfo("o","orthdist")); // use index 1 of FlagInfo container
flag_list.get<1>().insert(FlagInfo("f","fleetid")); // use index 1 of FlagInfo container
</code>

==== Find ====
<code cpp>
FlagList::nth_index<1>::type::iterator itr = flag_list.get<1>().find(flag); // use first index
if (itr != flag_list.get<1>().end()) {
    cout << itr->full_name << endl;
}
</code>
Small heaps of code

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