Beispiele 14.12.2023

20231214/dynmem-01.c

+#include <stdio.h>
+
+char *name[] = { "Anna", "Berthold", "Caesar" };
+
+int main (void)
+{
+  name[3] = "Dieter";
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  return 0;
+}

20231214/dynmem-02.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));  /* Speicherplatz für 3 Zeiger anfordern */
+  name[0] = "Anna";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+  name[3] = "Dieter";  /* immer noch unzulässig */
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20231214/dynmem-03.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));  /* Speicherplatz für 3 Zeiger anfordern */
+  name[0] = "Anna";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+//  name[3] = "Dieter";  /* immer noch unzulässig */
+  for (int i = 0; i < 3; i++)   /* vorher: 4 (unzulässig) */
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20231214/dynmem-04.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));  /* Speicherplatz für 3 Zeiger anfordern */
+  name[0] = "Anna";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+
+  char **new_name = malloc (4 * sizeof (char *));  /* Speicherplatz für 4 Zeiger anfordern */
+  for (int i = 0; i < 3; i++)
+    new_name[i] = name[i];
+  new_name[3] = "Dieter";
+
+  free (name);  /* altes Array */
+  name = new_name;  /* alter Zeiger zeigt auf neues Array */
+
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20231214/dynmem-05.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));  /* Speicherplatz für 3 Zeiger anfordern */
+  name[0] = "Anna";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+
+  char **new_name = malloc (4 * sizeof (char *));  /* Speicherplatz für 4 Zeiger anfordern */
+  for (int i = 0; i < 3; i++)
+    new_name[i] = name[i];
+  new_name[3] = "Dieter";
+
+  free (name);  /* altes Array */
+  name = new_name;  /* alter Zeiger zeigt auf neues Array */
+
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  free (new_name);  /* zeigt auf denselben Speicherplatz wie name --> Fehler */
+  return 0;
+}

20231214/dynmem-06.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));  /* Speicherplatz für 3 Zeiger anfordern */
+  name[0] = "Anna";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+
+  name = realloc (name, 4 * sizeof (char *));  /* Speicherplatz für 4 Zeiger anfordern */
+  name[3] = "Dieter";
+
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20231214/hello-gtk.png

+../common/hello-gtk.png
\ No newline at end of file

20231214/hp-20231214.tex

@@ -65,11 +65,10 @@
         \item[6.0] Dynamische Speicherverwaltung
         \item[6.1] Konzepte und Ziele
         \item[6.2] Beispiel: Zahlen und Buchstaben
-        \color{black}
         \item[6.3] Unions
         \item[6.4] Virtuelle Methoden
-        \vspace*{-\smallskipamount}
-        \item[\dots]
+        \item[6.5] Beispiel: Graphische Benutzeroberfläche (GUI)
+        \item[6.6] Ausblick: C++
       \end{itemize}
     \item[\textbf{7}] \textbf{Datenstrukturen}
   \end{itemize}
@@ -337,8 +336,8 @@
           \put(-2.75,-0.05){\tikz{\draw[thick](0,0.25)--(2.5,-0.05);%
                                   \draw[thick](-0.1,-0.05)--(2.5,0.3);}}
           \put(1.5,-1.1){\begin{rotate}{7}\large\bf\textarrow\
-%                           kommt gleich
-                           nächste Woche
+                           kommt gleich
+%                           nächste Woche
                          \end{rotate}}
         \end{picture}
         Zeiger, die im Objekt gespeichert sind\\
@@ -478,8 +477,6 @@
   
 \end{frame}
 
-\iffalse
-
 \subsection{Unions}
 
 \begin{frame}[fragile]
@@ -830,6 +827,4 @@
   
 \end{frame}
 
-\fi
-
 \end{document}

20231214/objects-01.c

+#include <stdio.h>
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+int main (void)
+{
+  t_integer i = { 1, 42 };
+  t_string s = { 2, "Hello, world!" };
+
+  t_base *object[] = { &i, &s };
+
+  return 0;
+}

20231214/objects-02.c

+#include <stdio.h>
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+int main (void)
+{
+  t_integer i = { 1, 42 };
+  t_string s = { 2, "Hello, world!" };
+
+  t_base *object[] = { (t_base *) &i, (t_base *) &s };
+
+  return 0;
+}

20231214/objects-03.c

+#include <stdio.h>
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+int main (void)
+{
+  t_integer i = { 1, 42 };
+  t_string s = { 2, "Hello, world!" };
+
+  t_base *object[] = { (t_base *) &i, (t_base *) &s };
+
+  for (int i = 0; i < 2; i++)
+    if (object[i]->type == 1)
+      printf ("Integer: %d\n", object[i]->content);
+    else if (object[i]->type == 2)
+      printf ("String: \"%s\"\n", object[i]->content);
+
+  return 0;
+}

20231214/objects-04.c

+#include <stdio.h>
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+int main (void)
+{
+  t_integer i = { 1, 42 };
+  t_string s = { 2, "Hello, world!" };
+
+  t_base *object[] = { (t_base *) &i, (t_base *) &s };
+
+  for (int i = 0; i < 2; i++)
+    if (object[i]->type == 1)
+      printf ("Integer: %d\n", (t_integer *) object[i]->content);
+    else if (object[i]->type == 2)
+      printf ("String: \"%s\"\n", (t_string *) object[i]->content);
+
+  return 0;
+}

20231214/objects-05.c

+#include <stdio.h>
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+int main (void)
+{
+  t_integer i = { 1, 42 };
+  t_string s = { 2, "Hello, world!" };
+
+  t_base *object[] = { (t_base *) &i, (t_base *) &s };
+
+  for (int i = 0; i < 2; i++)
+    if (object[i]->type == 1)
+      printf ("Integer: %d\n", ((t_integer *) object[i])->content);
+    else if (object[i]->type == 2)
+      printf ("String: \"%s\"\n", ((t_string *) object[i])->content);
+
+  return 0;
+}

20231214/objects-06.c

+#include <stdio.h>
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+void print_object (t_base *this)
+{
+  if (this->type == 1)
+    printf ("Integer: %d\n", ((t_integer *) this)->content);
+  else if (this->type == 2)
+    printf ("String: \"%s\"\n", ((t_string *) this)->content);
+}
+
+int main (void)
+{
+  t_integer i = { 1, 42 };
+  t_string s = { 2, "Hello, world!" };
+
+  t_base *object[] = { (t_base *) &i, (t_base *) &s };
+
+  for (int i = 0; i < 2; i++)
+    print_object (object[i]);
+
+  return 0;
+}

20231214/objects-07.c

+#include <stdio.h>
+
+#define T_BASE    0
+#define T_INTEGER 1
+#define T_STRING  2
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+void print_object (t_base *this)
+{
+  if (this->type == T_INTEGER)
+    printf ("Integer: %d\n", ((t_integer *) this)->content);
+  else if (this->type == T_STRING)
+    printf ("String: \"%s\"\n", ((t_string *) this)->content);
+}
+
+int main (void)
+{
+  t_integer i = { T_INTEGER, 42 };
+  t_string s = { T_STRING, "Hello, world!" };
+
+  t_base *object[] = { (t_base *) &i, (t_base *) &s, NULL };
+
+  for (int i = 0; object[i]; i++)
+    print_object (object[i]);
+
+  return 0;
+}

20231214/objects-08.c

+#include <stdio.h>
+#include <stdlib.h>
+
+#define T_BASE    0
+#define T_INTEGER 1
+#define T_STRING  2
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+void print_object (t_base *this)
+{
+  if (this->type == T_INTEGER)
+    printf ("Integer: %d\n", ((t_integer *) this)->content);
+  else if (this->type == T_STRING)
+    printf ("String: \"%s\"\n", ((t_string *) this)->content);
+}
+
+t_integer *new_integer (int i)
+{
+  t_integer *p = malloc (sizeof (t_integer));
+  p->type = T_INTEGER;
+  p->content = i;
+  return p;
+}
+
+t_string *new_string (char *s)
+{
+  t_string *p = malloc (sizeof (t_string));
+  p->type = T_STRING;
+  p->content = s;
+  return p;
+}
+
+int main (void)
+{
+  t_base *object[] = { (t_base *) new_integer (42),
+                       (t_base *) new_string ("Hello, world!"),
+                       NULL };
+
+  for (int i = 0; object[i]; i++)
+    print_object (object[i]);
+
+  return 0;
+}

20231214/objects-09.c

+#include <stdio.h>
+#include <stdlib.h>
+
+#define T_BASE    0
+#define T_INTEGER 1
+#define T_STRING  2
+
+typedef struct
+{
+  int type;
+} t_base;
+
+typedef struct
+{
+  int type;
+  int content;
+} t_integer;
+
+typedef struct
+{
+  int type;
+  char *content;
+} t_string;
+
+typedef union
+{
+  t_base base;
+  t_integer integer;
+  t_string string;
+} t_object;
+
+void print_object (t_object *this)
+{
+  if (this->base.type == T_INTEGER)
+    printf ("Integer: %d\n", this->integer.content);
+  else if (this->base.type == T_STRING)
+    printf ("String: \"%s\"\n", this->string.content);
+}
+
+t_object *new_integer (int i)
+{
+  t_object *p = malloc (sizeof (t_integer));
+  p->integer.type = T_INTEGER;
+  p->integer.content = i;
+  return p;
+}
+
+t_object *new_string (char *s)
+{
+  t_object *p = malloc (sizeof (t_string));
+  p->string.type = T_STRING;
+  p->string.content = s;
+  return p;
+}
+
+int main (void)
+{
+  t_object *object[] = { new_integer (42),
+                         new_string ("Hello, world!"),
+                         NULL };
+
+  for (int i = 0; object[i]; i++)
+    print_object (object[i]);
+
+  for (int i = 0; object[i]; i++)
+    free (object[i]);
+
+  return 0;
+}

20231214/objects-09a.c

+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct
+{
+} t_base;
+
+typedef struct
+{
+  int content;
+} t_integer;
+
+typedef struct
+{
+  char *content;
+} t_string;
+
+typedef union
+{
+  t_base base;
+  t_integer integer;
+  t_string string;
+} t_object;
+
+void print_object (t_object *this)
+{
+//   if (this->base.type == T_INTEGER)
+//     printf ("Integer: %d\n", this->integer.content);
+//   else if (this->base.type == T_STRING)
+//     printf ("String: \"%s\"\n", this->string.content);
+}
+
+t_object *new_integer (int i)
+{
+  t_object *p = malloc (sizeof (t_integer));
+  p->integer.content = i;
+  return p;
+}
+
+t_object *new_string (char *s)
+{
+  t_object *p = malloc (sizeof (t_string));
+  p->string.content = s;
+  return p;
+}
+
+int main (void)
+{
+  t_object *object[] = { new_integer (42),
+                         new_string ("Hello, world!"),
+                         NULL };
+
+  for (int i = 0; object[i]; i++)
+    print_object (object[i]);
+
+  for (int i = 0; object[i]; i++)
+    free (object[i]);
+
+  return 0;
+}

20231214/objects-09b.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct
+{
+} t_base;
+
+typedef struct
+{
+  int content;
+} t_integer;
+
+typedef struct
+{
+  char *content;
+} t_string;
+
+typedef union
+{
+  t_base base;
+  t_integer integer;
+  t_string string;
+} t_object;
+
+void print_object (t_object *this)
+{
+  printf ("Wenn dies eine Integer ist, dann lautet sie: %d.\n", this->integer.content);
+  printf ("Wenn dies ein String ist, ist er %zu Zeichen lang.\n",
+          strlen (this->string.content));
+}
+
+t_object *new_integer (int i)
+{
+  t_object *p = malloc (sizeof (t_integer));
+  p->integer.content = i;
+  return p;
+}
+
+t_object *new_string (char *s)
+{
+  t_object *p = malloc (sizeof (t_string));
+  p->string.content = s;
+  return p;
+}
+
+int main (void)
+{
+  t_object *object[] = { new_integer (42),
+                         new_string ("Hello, world!"),
+                         NULL };
+
+  for (int i = 0; object[i]; i++)
+    print_object (object[i]);
+
+  for (int i = 0; object[i]; i++)
+    free (object[i]);
+
+  return 0;
+}