Added hash example with std::hash specialisation

Grzegorz Jabłoński
1 parent c102e438
Showing 2 changed files with 46 additions and 1 deletions
examples09/05-unordered_set/makefile
examples09/05-unordered_set/unordered_set2.cpp
-all: unordered_set
+all: unordered_set unordered_set2
  
 unordered_set: unordered_set.o
 	g++ -g -Wall -pedantic $^ -o $@
@@ -6,6 +6,13 @@ unordered_set: unordered_set.o
 unoredered_set.o: unordered_set.cpp employee.h
 	g++ -g -c -Wall -pedantic $< -o $@
  
+unordered_set2: unordered_set2.o
+	g++ -g -Wall -pedantic $^ -o $@
+
+unoredered_set2.o: unordered_set2.cpp employee.h
+	g++ -g -c -Wall -pedantic $< -o $@
+
+
 .PHONY: clean
  
 clean:
+#include <functional>
+#include <unordered_set>
+using namespace std;
+#include "employee.h"
+
+template<> struct std::hash<Employee> 
+{
+  std::size_t operator()(const Employee & o) const
+  {
+    return std::hash <std::string>()(o.FirstName)
+         ^ (std::hash <std::string>()(o.LastName) << 1)
+         ^ (std::hash <std::string>()(o.ID) << 2);
+  }
+};
+
+void EmpsetPrint (const unordered_set <Employee> S, ostream & Out);
+
+int
+main ()
+{
+  Employee Ben ("Ben", "Keller", "000-00-0000");
+  Employee Bill ("Bill", "McQuain", "111-11-1111");
+  Employee Dwight ("Dwight", "Barnette", "888-88-8888");
+
+  unordered_set <Employee> S;
+  S.insert (Bill);
+  S.insert (Dwight);
+  S.insert (Ben);
+  EmpsetPrint (S, cout);
+}
+
+void
+EmpsetPrint (const unordered_set <Employee> S, ostream & Out)
+{
+  unordered_set <Employee>::const_iterator It;
+  for (It = S.begin (); It != S.end (); ++It)
+    Out << *It << endl;
+}