Beispiele und Notizen 27.6.2024

20240627/objects-19.cpp

+#include <stdio.h>
+
+struct TBase
+{
+  virtual void print ();
+};
+
+struct TInteger: TBase
+{
+  int content;
+  virtual void print ();
+  TInteger (int i);
+};
+
+struct TString: TBase
+{
+  const char *content;
+  virtual void print ();
+  TString (const char *s);
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = s;
+}
+
+int main (void)
+{
+  TBase *object[] = { new TInteger (42),
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-20.cpp

+#include <stdio.h>
+
+struct TBase
+{
+  void print ();
+};
+
+struct TInteger: TBase
+{
+  int content;
+  void print ();
+  TInteger (int i);
+};
+
+struct TString: TBase
+{
+  const char *content;
+  void print ();
+  TString (const char *s);
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = s;
+}
+
+int main (void)
+{
+  TBase *object[] = { new TInteger (42),
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-21.cpp

+#include <stdio.h>
+
+struct TBase
+{
+  virtual void print ();
+  virtual ~Base ();
+};
+
+struct TInteger: TBase
+{
+  int content;
+  virtual void print ();
+  TInteger (int i);
+};
+
+struct TString: TBase
+{
+  char *content;
+  virtual void print ();
+  TString (const char *s);
+  virtual ~TString ();
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+TBase::~TBase ()
+{
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = malloc (strlen (s) + 1);
+  strcpy (content, s);
+}
+
+TString::~TString ()
+{
+  free (content);
+}
+
+int main (void)
+{
+  TBase *object[] = { new TInteger (42),
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-22.cpp

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct TBase
+{
+  virtual void print ();
+  virtual ~TBase ();
+};
+
+struct TInteger: TBase
+{
+  int content;
+  virtual void print ();
+  TInteger (int i);
+};
+
+struct TString: TBase
+{
+  char *content;
+  virtual void print ();
+  TString (const char *s);
+  virtual ~TString ();
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+TBase::~TBase ()
+{
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = malloc (strlen (s) + 1);
+  strcpy (content, s);
+}
+
+TString::~TString ()
+{
+  free (content);
+}
+
+int main (void)
+{
+  TBase *object[] = { new TInteger (42),
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-23.cpp

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct TBase
+{
+  virtual void print ();
+  virtual ~TBase ();
+};
+
+struct TInteger: TBase
+{
+  int content;
+  virtual void print ();
+  TInteger (int i);
+};
+
+struct TString: TBase
+{
+  char *content;
+  virtual void print ();
+  TString (const char *s);
+  virtual ~TString ();
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+TBase::~TBase ()
+{
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = (char *) malloc (strlen (s) + 1);
+  strcpy (content, s);
+}
+
+TString::~TString ()
+{
+  free (content);
+}
+
+int main (void)
+{
+  TBase *object[] = { new TInteger (42),
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-24.cpp

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+class TBase
+{
+  virtual void print ();
+  virtual ~TBase ();
+};
+
+class TInteger: TBase
+{
+  int content;
+  virtual void print ();
+  TInteger (int i);
+};
+
+class TString: TBase
+{
+  char *content;
+  virtual void print ();
+  TString (const char *s);
+  virtual ~TString ();
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+TBase::~TBase ()
+{
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = (char *) malloc (strlen (s) + 1);
+  strcpy (content, s);
+}
+
+TString::~TString ()
+{
+  free (content);
+}
+
+int main (void)
+{
+  TBase *object[] = { new TInteger (42),
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-25.cpp

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+class TBase
+{
+public:
+  virtual void print ();
+  virtual ~TBase ();
+};
+
+class TInteger: public TBase
+{
+private:
+  int content;
+public:
+  virtual void print ();
+  TInteger (int i);
+};
+
+class TString: public TBase
+{
+private:
+  char *content;
+public:
+  virtual void print ();
+  TString (const char *s);
+  virtual ~TString ();
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+TBase::~TBase ()
+{
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = (char *) malloc (strlen (s) + 1);
+  strcpy (content, s);
+}
+
+TString::~TString ()
+{
+  free (content);
+}
+
+int main (void)
+{
+  TBase *object[] = { new TInteger (42),
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-26.cpp

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+class TBase
+{
+public:
+  virtual void print ();
+  virtual ~TBase ();
+};
+
+class TInteger: public TBase
+{
+private:
+  int content;
+public:
+  virtual void print ();
+  TInteger (int i);
+};
+
+class TString: public TBase
+{
+private:
+  char *content;
+public:
+  virtual void print ();
+  TString (const char *s);
+  virtual ~TString ();
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+TBase::~TBase ()
+{
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = (char *) malloc (strlen (s) + 1);
+  strcpy (content, s);
+}
+
+TString::~TString ()
+{
+  free (content);
+}
+
+int main (void)
+{
+  TInteger *answer = new TInteger (42);
+  TBase *object[] = { answer,
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  printf ("The answer is: %d.\n", answer->content);
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/objects-27.cpp

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+class TBase
+{
+public:
+  virtual void print ();
+  virtual ~TBase ();
+};
+
+class TInteger: public TBase
+{
+private:
+  int content;
+public:
+  virtual void print ();
+  TInteger (int i);
+  friend int main ();
+};
+
+class TString: public TBase
+{
+private:
+  char *content;
+public:
+  virtual void print ();
+  TString (const char *s);
+  virtual ~TString ();
+};
+
+void TBase::print ()
+{
+  printf ("Base\n");
+}
+
+TBase::~TBase ()
+{
+}
+
+void TInteger::print ()
+{
+  printf ("Integer: %d\n", content);
+}
+
+void TString::print ()
+{
+  printf ("String: \"%s\"\n", content);
+}
+
+TInteger::TInteger (int i)
+{
+  content = i;
+}
+
+TString::TString (const char *s)
+{
+  content = (char *) malloc (strlen (s) + 1);
+  strcpy (content, s);
+}
+
+TString::~TString ()
+{
+  free (content);
+}
+
+int main (void)
+{
+  TInteger *answer = new TInteger (42);
+  TBase *object[] = { answer,
+                      new TString ("Hello, world!"),
+                      NULL };
+
+  for (int i = 0; object[i]; i++)
+    object[i]->print ();
+
+  printf ("The answer is: %d.\n", answer->content);
+
+  for (int i = 0; object[i]; i++)
+    delete object[i];
+
+  return 0;
+}

20240627/strings-01.cpp

+#include <iostream>
+#include <string>
+
+int main ()
+{
+  string hello = "Hello, world!";
+  cout << hello << endl;
+  return 0;
+}

20240627/strings-02.cpp

+#include <iostream>
+#include <string>
+
+using std::string, std::cout, std::endl;
+
+int main ()
+{
+  string hello = "Hello, world!";
+  cout << hello << endl;
+  return 0;
+}

20240627/strings-03.cpp

+#include <stdio.h>
+#include <string>
+
+using std::string;
+
+int main ()
+{
+  string hello = "Hello, world!";
+  printf ("%s\n", hello);
+  return 0;
+}

20240627/strings-04.cpp

+#include <stdio.h>
+#include <string>
+
+using std::string;
+
+int main ()
+{
+  string hello = "Hello, world!";
+  printf ("%s\n", hello.c_str ());
+  return 0;
+}

20240627/strings-05.cpp

+#include <stdio.h>
+
+int main ()
+{
+  char answer[100];
+  snprintf (answer, 100, "The answer is %d.", 42);
+  printf ("%s\n", answer);
+  return 0;
+}

20240627/strings-06.cpp

+#include <sstream>
+#include <iostream>
+
+using std::ostringstream, std::cout, std::endl;
+
+int main ()
+{
+  ostringstream answer;
+  answer << "The answer is " << 42 << ".";
+  cout << answer << endl;
+  return 0;
+}

20240627/strings-07.cpp

+#include <sstream>
+#include <iostream>
+
+using std::ostringstream, std::cout, std::endl;
+
+int main ()
+{
+  ostringstream answer;
+  answer << "The answer is " << 42 << ".";
+  cout << answer.str () << endl;
+  return 0;
+}