Beispiel-Programme 11.10.2021

20211011/functions-1.c

+#include <stdio.h>
+
+int answer (void)
+{
+  return 42;
+}
+
+void foo (void)
+{
+  printf ("%d\n", answer ());
+}
+
+int main (void)
+{
+  foo ();
+  return 0;
+}

20211011/functions-10.c

+#include <stdio.h>
+
+int a = 0;
+int b = 3;
+
+void foo (void)
+{
+  b++;
+  static int a = 5;
+  int b = 7;
+  printf ("foo(): " "a = %d, b = %d\n", a, b);
+  a++;
+}
+
+int main (void)
+{
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  a = b = 12;
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+
+  return 0;
+
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+}

20211011/functions-11.c

+#include <stdio.h>
+
+int a = 0;
+int b = 3;
+
+void foo (void)
+{
+  b++;
+  static int a = 5;
+  int b = 7;
+  printf ("foo(): " "a = %d, b = %d\n", a, b);
+  a++;
+}
+
+int main (void)
+{
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  a = b = 12;
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  return 0;
+}

20211011/functions-2.c

+#include <stdio.h>
+
+void add_verbose (int a, int b)
+{
+  printf ("%d + %d = %d\n", a, b, a + b);
+}
+
+int main (void)
+{
+  add_verbose (3, 7);
+  return 0;
+}

20211011/functions-3.c

+#include <stdio.h>
+
+int add_verbose (int a, int b)
+{
+  printf ("%d + %d = %d\n", a, b, a + b);
+  return 42;
+}
+
+int main (void)
+{
+  add_verbose (3, 7);
+  return 0;
+}

20211011/functions-4.c

+#include <stdio.h>
+
+int add_verbose (int a, int b)
+{
+  printf ("%d + %d = %d\n", a, b, a + b);
+  return 42;
+}
+
+int main (void)
+{
+  int a = add_verbose (3, 7);
+  printf ("Rückgabewert: %d\n", a);
+  return 0;
+}

20211011/functions-5.c

+#include <stdio.h>
+
+void add_verbose (int a, int b)
+{
+  printf ("%d + %d = %d\n", a, b, a + b);
+  return 42;
+}
+
+int main (void)
+{
+  void a = add_verbose (3, 7);
+  printf ("Rückgabewert: %d\n", a);
+  return 0;
+}

20211011/functions-6.c

+#include <stdio.h>
+
+int a, b = 3;
+
+void foo (void)
+{
+  b++;
+  static int a = 5;
+  int b = 7;
+  printf ("foo(): " "a = %d, b = %d\n", a, b);
+  a++;
+}
+
+int main (void)
+{
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+
+  return 0;
+
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  a = b = 12;
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+}

20211011/functions-7.c

+#include <stdio.h>
+
+int a = 0;
+int b = 3;
+
+void foo (void)
+{
+  b++;
+  static int a = 5;
+  int b = 7;
+  printf ("foo(): " "a = %d, b = %d\n", a, b);
+  a++;
+}
+
+int main (void)
+{
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+
+  return 0;
+
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  a = b = 12;
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+}

20211011/functions-8.c

+#include <stdio.h>
+
+int a = 0;
+int b = 3;
+
+void foo (void)
+{
+  b++;
+  static int a = 5;
+  int b = 7;
+  printf ("foo(): " "a = %d, b = %d\n", a, b);
+  a++;
+}
+
+int main (void)
+{
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+
+  return 0;
+
+  a = b = 12;
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+}

20211011/functions-9.c

+#include <stdio.h>
+
+int a = 0;
+int b = 3;
+
+void foo (void)
+{
+  b++;
+  static int a = 5;
+  int b = 7;
+  printf ("foo(): " "a = %d, b = %d\n", a, b);
+  a++;
+}
+
+int main (void)
+{
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+  a = b = 12;
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+
+  return 0;
+
+  foo ();
+  printf ("main(): " "a = %d, b = %d\n", a, b);
+}

20211011/hp-20211011.tex

@@ -437,7 +437,8 @@
         Apple Mac OS: \file{Xcode}
       \item
         Microsoft Windows: \file{Cygwin}\\
-        oder \file{MinGW} mit \file{MSYS}
+        oder \file{MinGW} mit \file{MSYS}\\
+        oder \file{WSL} mit \file{Xming}
       \medskip
       \item
         außerdem: Texteditor\\

20211011/pointers-1.c

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

20211011/pointers-2.c

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

20211011/pointers-3-O0.s

+	.file	"pointers-3.c"
+	.text
+	.globl	calc_answer
+	.type	calc_answer, @function
+calc_answer:
+.LFB0:
+	.cfi_startproc
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	movq	%rdi, -8(%rbp)
+	movq	-8(%rbp), %rax
+	movl	$42, (%rax)
+	nop
+	popq	%rbp
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	calc_answer, .-calc_answer
+	.section	.rodata
+.LC0:
+	.string	"The answer is %d.\n"
+	.text
+	.globl	main
+	.type	main, @function
+main:
+.LFB1:
+	.cfi_startproc
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	subq	$16, %rsp
+	movl	-4(%rbp), %eax
+	cltq
+	movq	%rax, %rdi
+	call	calc_answer
+	movl	-4(%rbp), %eax
+	movl	%eax, %esi
+	leaq	.LC0(%rip), %rdi
+	movl	$0, %eax
+	call	printf@PLT
+	movl	$0, %eax
+	leave
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc
+.LFE1:
+	.size	main, .-main
+	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
+	.section	.note.GNU-stack,"",@progbits

20211011/pointers-3-O1.s

+	.file	"pointers-3.c"
+	.text
+	.globl	calc_answer
+	.type	calc_answer, @function
+calc_answer:
+.LFB11:
+	.cfi_startproc
+	movl	$42, (%rdi)
+	ret
+	.cfi_endproc
+.LFE11:
+	.size	calc_answer, .-calc_answer
+	.section	.rodata.str1.1,"aMS",@progbits,1
+.LC0:
+	.string	"The answer is %d.\n"
+	.text
+	.globl	main
+	.type	main, @function
+main:
+.LFB12:
+	.cfi_startproc
+	subq	$8, %rsp
+	.cfi_def_cfa_offset 16
+	movl	$0, %esi
+	leaq	.LC0(%rip), %rdi
+	movl	$0, %eax
+	call	printf@PLT
+	movl	$0, %eax
+	addq	$8, %rsp
+	.cfi_def_cfa_offset 8
+	ret
+	.cfi_endproc
+.LFE12:
+	.size	main, .-main
+	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
+	.section	.note.GNU-stack,"",@progbits

20211011/pointers-3.c

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

20211011/side-effects-1.c

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

20211011/side-effects-10.c

+#include <stdio.h>
+
+int main (void)
+{
+  double pi = 3.14159;
+  printf ("pi = %lf\n", pi);
+  return 0;
+}