Beispiele 30.3.2023

20230323/functions-03a.c

+#include <stdio.h>
+
+void print (const char *s)
+{
+  printf ("%s", s);
+}
+
+void print (int i)
+{
+  printf ("%d", i);
+}
+
+int main ()
+{
+  print ("Hello, world!\n");
+  print (42);
+  print ();
+}

20230323/void-07.c

+#include <stdio.h>
+
+hello ()
+{
+  printf ("Hello, world!\n");
+  return 42;
+}
+
+main ()
+{
+  hello ("Wörldt");
+  return 0;
+}

20230330/ad-20230330.tex

@@ -442,16 +442,19 @@
       \lstinline{class}: standardmäßig \lstinline{private}
     \medskip
     \item
-      \lstinline{friend}-Funktionen und -Klassen
-    \medskip
-    \item
-      Klasse als Namensraum:\\
-      \lstinline{static}-"`Member"'-Variable\\
-      \lstinline{static}-"`Methoden"'\\
-      Deklarationen von z.\,B.\ Konstanten und Typen
+      \dots
+%      \lstinline{friend}-Funktionen und -Klassen
+%    \medskip
+%    \item
+%      Klasse als Namensraum:\\
+%      \lstinline{static}-"`Member"'-Variable\\
+%      \lstinline{static}-"`Methoden"'\\
+%      Deklarationen von z.\,B.\ Konstanten und Typen
   \end{itemize}
 \end{frame}
 
+\iffalse
+
 \addtocounter{subsection}{-1}
 \subsection{Objekte: Konstruktoren und Destruktoren}
 
@@ -491,8 +494,6 @@
   \end{itemize}
 \end{frame}
 
-\iffalse
-
 \subsection{Templates}
 
 \begin{frame}[fragile]

20230330/const-01.c

+#include <stdio.h>
+
+#define n 5
+
+int prime[n] = { 2, 3, 5, 7, 11 };
+
+int main (void)
+{
+  for (int i = 0; i < n; i++)
+    printf ("%d\n", prime[i]);
+  return 0;
+}

20230330/const-02.c

+#include <stdio.h>
+
+const int n = 5;
+
+int prime[n] = { 2, 3, 5, 7, 11 };
+
+int main (void)
+{
+  for (int i = 0; i < n; i++)
+    printf ("%d\n", prime[i]);
+  return 0;
+}

20230330/const-03.c

+#include <stdio.h>
+
+const int n = 5;
+
+int main (void)
+{
+  printf ("n = %d\n", n);
+  n = 6;
+  printf ("n = %d\n", n);
+  return 0;
+}

20230330/const-04.c

+#include <stdio.h>
+
+const int n = 5;
+
+int main (void)
+{
+  printf ("n = %d\n", n);
+  int *p = &n;
+  *p = 6;
+  printf ("n = %d\n", n);
+  return 0;
+}

20230330/const-05.c

+#include <stdio.h>
+
+const int n = 5;
+
+int main (void)
+{
+  printf ("n = %d\n", n);
+  const int *p = &n;
+  *p = 6;
+  printf ("n = %d\n", n);
+  return 0;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}

20230330/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;
+}