Beispielprogramme 9.4.2018: Zeiger

20180409/pointers-1.c

+#include <stdio.h>
+
+void calc_answer (int a)
+{
+  a = 42;
+}
+
+int main (void)
+{
+  int a;
+  calc_answer (a);
+  printf ("The answer is: %d\n", a);
+  return 0;
+}

20180409/pointers-2.c

+#include <stdio.h>
+
+void calc_answer (int a)
+{
+  a = 42;
+}
+
+int main (void)
+{
+  int a = 137;
+  calc_answer (a);
+  printf ("The answer is: %d\n", a);
+  return 0;
+}

20180409/pointers-3.c

+#include <stdio.h>
+
+void calc_answer (int *a)
+{
+  *a = 42;
+}
+
+int main (void)
+{
+  int a = 137;
+  calc_answer (&a);
+  printf ("The answer is: %d\n", a);
+  return 0;
+}

20180409/pointers-4.c

+#include <stdio.h>
+
+void calc_answer (int **a)
+{
+  int beta = 42;
+  *a = &beta;
+}
+
+int main (void)
+{
+  int alpha = 137;
+  int *a = &alpha;
+  calc_answer (&a);
+  printf ("The answer is: %d\n", *a);
+  return 0;
+}

20180409/pointers-5.c

+#include <stdio.h>
+
+void calc_answer (int **a)
+{
+  static int beta = 42;
+  *a = &beta;
+}
+
+int main (void)
+{
+  int alpha = 137;
+  int *a = &alpha;
+  calc_answer (&a);
+  printf ("The answer is: %d\n", *a);
+  return 0;
+}

20180409/pointers-6.c

+#include <stdio.h>
+
+void calc_answer (int **a)
+{
+  **a = 42;
+}
+
+int main (void)
+{
+  int alpha = 137;
+  int *a = &alpha;
+  calc_answer (&a);
+  printf ("The answer is: %d\n", *a);
+  return 0;
+}