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--- cppcookbook [2012/04/11 00:05]
mantis [Example: creating a lookup table for flags and full names]
+++ cppcookbook [2012/04/11 09:42] (current)
mantis
@@ Line 1: / Line 1: @@
+====== 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>

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