Beispielprogramme 12.12.2016

Tafelbilder 14.12.2016: Binärdarstellung negativer Zahlen
README.md statt README

20161212/dynmem-1.c

+#include <stdio.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));
+  name[0] = "Anton";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+  for (int i = 0; i < 3; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20161212/dynmem-2.c

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

20161212/dynmem-3.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));
+  name[0] = "Anton";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+
+  char **new_name = malloc (4 * sizeof (char*));
+  for (int i = 0; i < 3; i++)
+    new_name[i] = name[i];
+  name = new_name;   /* Speicherleck: Array wurde nicht freigegeben! */
+
+  name[3] = "Dieter";
+
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20161212/dynmem-4.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));
+  name[0] = "Anton";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+
+  char **new_name = malloc (4 * sizeof (char*));
+  for (int i = 0; i < 3; i++)
+    new_name[i] = name[i];
+  free (name);
+  name = new_name;   /* kein Speicherleck: Array wurde freigegeben. */
+
+  name[3] = "Dieter";
+
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20161212/dynmem-5.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));
+  name[0] = "Anton";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+
+  char **new_name = malloc (4 * sizeof (char*));
+  for (int i = 0; i < 3; i++)
+    new_name[i] = name[i];
+  free (name);
+  name = new_name;
+
+  name[3] = "Dieter";
+
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  free (new_name);   /* Fehler: Array wurde bereits freigegeben! */
+  return 0;
+}

20161212/dynmem-6.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));
+  name[0] = "Anton";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+
+  char **new_name = malloc (4 * sizeof (char*));
+  for (int i = 0; i < 3; i++)
+    new_name[i] = name[i];
+  free (name);
+  name = new_name;
+  new_name = NULL;   /* Zeiger wird nicht mehr gebraucht. */
+
+  name[3] = "Dieter";
+
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20161212/dynmem-7.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));
+  name[0] = "Anton";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+  name = realloc (name, 4 * sizeof (char));
+  name[3] = "Dieter";        /* Fehler: ^ "*" vergessen; zu wenig Speicher */
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20161212/dynmem-8.c

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

20161212/dynmem-9.c

+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+  char **name = malloc (3 * sizeof (char *));
+  name[0] = "Anton";
+  name[1] = "Berthold";
+  name[2] = "Caesar";
+  name = realloc (name, 4 * sizeof (char));
+  name[3] = "Dieter";        /* Fehler: ^ "*" vergessen; zu wenig Speicher */
+  for (int i = 0; i < 4; i++)
+    printf ("%s\n", name[i]);
+  free (name);
+  return 0;
+}

20161212/objects-6.c

@@ -17,6 +17,14 @@ typedef struct
   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 };
@@ -25,10 +33,7 @@ int main (void)
   t_base *object[] = { (t_base *) &i, (t_base *) &s };
 
   for (int i = 0; i < 2; i++)
-    if (object[i]->type == 2)
-      printf ("Integer: %d\n", ((t_integer *) object[i])->content);
-    else if (object[i]->type == 1)
-      printf ("String: \"%s\"\n", ((t_string *) object[i])->content);
+    print_object (object[i]);
 
   return 0;
 }

20161212/objects-7.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;
-
-typedef union
-{
-  t_base base;
-  t_integer integer;
-  t_string string;
-} t_object;
-
-int main (void)
-{
-  t_object i = { integer: { 1, 42 } };
-  t_object s = { string: { 2, "Hello, world!" } };
-
-  t_object *object[] = { &i, &s };
-
-  for (int i = 0; i < 2; i++)
-    if (object[i]->base.type == 1)
-      printf ("Integer: %d\n", ((t_integer *) object[i])->content);
-    else if (object[i]->base.type == 2)
-      printf ("String: \"%s\"\n", ((t_string *) object[i])->content);
-
-  return 0;
-}

20161212/objects-8.c

-#include <stdio.h>
-
-union t_object;
-
-typedef struct
-{
-  void (* print) (union t_object *this);
-} t_base;
-
-typedef struct
-{
-  void (* print) (union t_object *this);
-  int content;
-} t_integer;
-
-typedef struct
-{
-  void (* print) (union t_object *this);
-  char *content;
-} t_string;
-
-typedef union t_object
-{
-  t_base base;
-  t_integer integer;
-  t_string string;
-} t_object;
-
-void print_integer (t_object *this)
-{
-  printf ("Integer: %d\n", this->integer.content);
-}
-
-void print_string (t_object *this)
-{
-  printf ("String: %s\n", this->string.content);
-}
-
-int main (void)
-{
-  t_object i = { integer: { print_integer, 42 } };
-  t_object s = { string: { print_string, "Hello, world!" } };
-
-  t_object *object[] = { &i, &s };
-
-  for (int i = 0; i < 2; i++)
-    object[i]->base.print (object[i]);
-
-  return 0;
-}

20161212/objects-9.c

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

README → README.md

 Hardwarenahe Programmierung
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+===========================
+
 Lehrveranstaltung im Wintersemester 2016/17
 Hochschule Bochum, Campus Velbert/Heiligenhaus
 Prof. Dr. rer. nat. Peter Gerwinski
 
-Copyright (C) 2012-2016  Peter Gerwinski
+Copyright (C) 2012–2016  Peter Gerwinski
 
-  common   - gemeinsame Dateien für Skript und Vortragsfolien
-  script   - Skript zur Lehrveranstaltung
-  201????? - Vortragsfolien und Beispiele
+ * common   – gemeinsame Dateien für Skript und Vortragsfolien
+ * script   – Skript zur Lehrveranstaltung
+ * 201????? – Vortragsfolien und Beispiele
 
 Diese Lehrmaterialien sind freie Software. Sie dürfen diese
 gemäß den jeweils angegebenen Lizenzen (CC-BY-SA 3.0, GNU GPL 3+,
@@ -17,16 +18,17 @@ weitergeben. Für Details siehe common/README.
 
 
 Low-Level Programming
-~~~~~~~~~~~~~~~~~~~~~
+=====================
+
 Course in winter semester 2016-17
 Bochum University of Applied Sciences, Campus Velbert/Heiligenhaus
 Prof. Dr. rer. nat. Peter Gerwinski
 
-Copyright (C) 2012-2016  Peter Gerwinski
+Copyright (C) 2012–2016  Peter Gerwinski
 
-  common   - common files for lecture notes and slides
-  script   - lecture notes
-  201????? - slides and examples
+ * common   – common files for lecture notes and slides
+ * script   – lecture notes
+ * 201????? – slides and examples
 
 This teaching materials are Free Software. You may study, copy,
 modify, and/or distribute them according to their respective