diff --git a/ch21/const b/ch21/const
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Binary files /dev/null and b/ch21/const differ
diff --git a/ch21/const.cc b/ch21/const.cc
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+++ b/ch21/const.cc
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+#include <iostream>
+
+using namespace std;
+
+class FirstClass {     
+ public:
+  void print1() {
+    std::cout << "FirstClass::print1()" << std::endl;
+  }
+  virtual void print2() {
+    std::cout << "FirstClass::print2()" << std::endl;
+  }
+  void print3() {
+    print1();
+    print2();
+  }
+};
+
+class SecondClass : public FirstClass {     
+ public:
+  void print1() {
+    std::cout << "SecondClass::print1()" << std::endl;
+  }
+  virtual void print2() {
+    std::cout << "SecondClass::print2()" << std::endl;
+  }
+};
+
+class ThirdClass : public SecondClass {     
+ public:
+  void print1() {
+    std::cout << "ThirdClass::print1()" << std::endl;
+  }
+  virtual void print2() {
+    std::cout << "ThirdClass::print2()" << std::endl;
+  }
+};
+
+int main(int argc, char **argv) {
+  FirstClass x;
+  x.print1();
+  x.print2();
+  x.print3();
+
+  std::cout << std::endl;
+
+  SecondClass y;
+  y.print1();
+  y.print2();
+  y.print3();
+
+  std::cout << std::endl;
+  
+  ThirdClass z;
+  z.print1();
+  z.print2();
+  z.print3();
+  
+  return 0;
+}
+
+// FirstClass::print1()
+// FirstClass::print2()
+// FirstClass::print1()
+// FirstClass::print2()
+
+// SecondClass::print1()
+// SecondClass::print2()
+// FirstClass::print1()
+// SecondClass::print2()
+
+// ThirdClass::print1()
+// ThirdClass::print2()
+// FirstClass::print1()
+// ThirdClass::print2()
diff --git a/ch22/IntegerMapping.cc b/ch22/IntegerMapping.cc
new file mode 100644
index 0000000..c9bd6e4
--- /dev/null
+++ b/ch22/IntegerMapping.cc
@@ -0,0 +1,49 @@
+#include <iostream>
+
+using namespace std;
+
+class IntegerMapping {     
+ public:
+  virtual int maps(int x) const = 0;
+};
+
+class Translation : public IntegerMapping {     
+ public:
+  Translation(int l) : k(l) {}
+  int maps(int x) const {
+    return x+k;
+  }
+ private:
+  int k;
+};
+
+class Negate : public IntegerMapping {     
+ public:
+  Negate() {}
+  int maps(int x) const {
+    return -x;
+  }
+};
+
+class Compose : public IntegerMapping {     
+ public:
+  Compose(IntegerMapping &n1, IntegerMapping &n2) : m1(&n1), m2(&n2) {}
+  int maps(int x) const {
+    return m1->maps(m2->maps(x));
+  }
+ private:
+  IntegerMapping *m1;
+  IntegerMapping *m2;
+};
+
+int weird(IntegerMapping *m, int a, int b) {
+  return m->maps(a) * m->maps(b);
+}
+
+int main(int argc, char **argv) {
+  Translation t(5);
+  Negate n;
+  Compose c(&t, &n);
+  cout << weird(&c, 15, 16) << endl;
+  return 0;
+}
diff --git a/ch22/VectorMaping b/ch22/VectorMaping
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diff --git a/ch22/VectorMaping.cc b/ch22/VectorMaping.cc
new file mode 100644
index 0000000..bfd7eb6
--- /dev/null
+++ b/ch22/VectorMaping.cc
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+#include <iostream>
+
+using namespace std;
+
+class IntegerMapping {     
+ public:
+  virtual int maps(int x) const = 0;
+};
+
+class Negate : public IntegerMapping {     
+ public:
+  Negate() {}
+  int maps(int x) const {
+    return -x;
+  }
+};
+
+class VectorMaping {     
+ public:
+  virtual int *maps(int *c, int s) const = 0;
+};
+
+class Shift : public VectorMaping {     
+ public:
+  Shift(int l) : k(l) {}
+  int *maps(int *c, int s) const {
+    int *result = new int[s];
+    for (int j = 0; j < s; j++) {
+      result[j] = c[(j+k)%s];
+    }
+    return result;
+  }
+ private:
+  int k;
+};
+
+class MetaMaping : public VectorMaping {     
+ public:
+  MetaMaping(const IntegerMapping &m) : im(&m) {}
+  int *maps(int *c, int s) const {
+    int *result = new int[s];
+    for (int k = 0; k < s; k++) {
+      result[k] = im->maps(c[k]);
+    }
+    return result;
+  }
+ private:
+  const IntegerMapping *im;
+};
+
+void print(const VectorMaping &vm, int *c, int s) {
+  int *t = vm.maps(c, s);
+  for (int j = 0; j < s; j++) {
+	std::cout << t[j];
+    if (j < s-1) {
+      std::cout << " ";
+    } else {
+      std::cout << std::endl;
+    }
+  }
+  delete[] t;
+}
+
+int main(int argc, char **argv) {
+  int v[] = {1, 2, 3, 4};
+  print(Shift(3), v, sizeof(v)/sizeof(int));
+  print(MetaMaping(Negate()), v, sizeof(v)/sizeof(int));
+  
+  return 0;
+}
+
+