diff --git a/Makefile b/Makefile
index 27041c7..c5f051a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 SRCS = $(wildcard src/*.c)
 PROGS = $(patsubst src/%.c,%,$(SRCS))
 
-CFLAGS += -g -Wall -O0 -ansi -static
+CFLAGS += -g -Wall -O0 -ansi
 VPATH = src/
 
 all: $(PROGS)
diff --git a/bin/1_n_a_factorial b/bin/1_n_a_factorial
index 9fe91bb..eb1874f 100755
Binary files a/bin/1_n_a_factorial and b/bin/1_n_a_factorial differ
diff --git a/bin/1_n_b_ascii b/bin/1_n_b_ascii
index 7bd455f..59d2b26 100755
Binary files a/bin/1_n_b_ascii and b/bin/1_n_b_ascii differ
diff --git a/bin/1_p_a_kanten b/bin/1_p_a_kanten
index fb62352..6e8e3de 100755
Binary files a/bin/1_p_a_kanten and b/bin/1_p_a_kanten differ
diff --git a/bin/1_v_a_square b/bin/1_v_a_square
index f97d3ca..fb46c42 100755
Binary files a/bin/1_v_a_square and b/bin/1_v_a_square differ
diff --git a/bin/2_p_b_raten b/bin/2_p_b_raten
index a7a223a..afb2432 100755
Binary files a/bin/2_p_b_raten and b/bin/2_p_b_raten differ
diff --git a/bin/2_p_c_tree b/bin/2_p_c_tree
index 8f8d156..8848ea9 100755
Binary files a/bin/2_p_c_tree and b/bin/2_p_c_tree differ
diff --git a/bin/2_p_d_einXeins b/bin/2_p_d_einXeins
index 3d3cb0a..ff7b12b 100755
Binary files a/bin/2_p_d_einXeins and b/bin/2_p_d_einXeins differ
diff --git a/bin/2_v_b_logic b/bin/2_v_b_logic
index d5ef36d..a63434b 100755
Binary files a/bin/2_v_b_logic and b/bin/2_v_b_logic differ
diff --git a/bin/3_n_a_xor_encryption b/bin/3_n_a_xor_encryption
index ce9114b..071fe97 100755
Binary files a/bin/3_n_a_xor_encryption and b/bin/3_n_a_xor_encryption differ
diff --git a/bin/3_n_b_scalarm b/bin/3_n_b_scalarm
index 0cd595e..686ed3b 100755
Binary files a/bin/3_n_b_scalarm and b/bin/3_n_b_scalarm differ
diff --git a/bin/3_n_c_userdb b/bin/3_n_c_userdb
index 71a285e..edc219c 100755
Binary files a/bin/3_n_c_userdb and b/bin/3_n_c_userdb differ
diff --git a/bin/3_p_a_zaehlen b/bin/3_p_a_zaehlen
index 400ca21..5728014 100755
Binary files a/bin/3_p_a_zaehlen and b/bin/3_p_a_zaehlen differ
diff --git a/bin/3_p_b_transponieren b/bin/3_p_b_transponieren
index 145c170..e2efbc7 100755
Binary files a/bin/3_p_b_transponieren and b/bin/3_p_b_transponieren differ
diff --git a/bin/3_p_c_parteien b/bin/3_p_c_parteien
index 85bb260..f05abc8 100755
Binary files a/bin/3_p_c_parteien and b/bin/3_p_c_parteien differ
diff --git a/bin/4_n_a_swap2 b/bin/4_n_a_swap2
new file mode 100755
index 0000000..363e80c
Binary files /dev/null and b/bin/4_n_a_swap2 differ
diff --git a/bin/4_n_b_strlen b/bin/4_n_b_strlen
new file mode 100755
index 0000000..a051a34
Binary files /dev/null and b/bin/4_n_b_strlen differ
diff --git a/bin/4_p_a_swap b/bin/4_p_a_swap
new file mode 100755
index 0000000..dc83f6c
Binary files /dev/null and b/bin/4_p_a_swap differ
diff --git a/bin/4_p_c_strings b/bin/4_p_c_strings
new file mode 100755
index 0000000..b1c59cc
Binary files /dev/null and b/bin/4_p_c_strings differ
diff --git a/src/4_n_a_swap2.c b/src/4_n_a_swap2.c
new file mode 100644
index 0000000..e36d377
--- /dev/null
+++ b/src/4_n_a_swap2.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+
+int i = 0;
+
+void swap (int * x, int * y) {
+	int temp;
+	temp = *x;
+	*x = *y;
+	*y = temp;
+}
+
+int f() {
+	i++;
+	return i;
+}
+
+int main () {
+	int feld[4] = {4, 3, 2, 1};
+	int zahl1 = 5, zahl2 = 3;
+
+	/* 2. Aufgabenteil */
+	printf("vor swap: zahl1=%d, zahl2=%d\n", zahl1, zahl2);
+	swap(&zahl1, &zahl2);
+	printf("nach swap: zahl1=%d, zahl2=%d\n", zahl1, zahl2);
+
+	/* 3. Aufgabenteil */
+	printf ("feld-Inhalt vor swap: {%d, %d, %d, %d}\n", feld[0], feld[1], feld[2], feld[3]);
+	swap (&i, &feld[f()]);
+	printf ("feld-Inhalt nach swap: {%d, %d, %d, %d}\n", feld[0], feld[1], feld[2], feld[3]);
+
+	return 0;
+}
+
diff --git a/src/4_n_b_strlen.c b/src/4_n_b_strlen.c
new file mode 100644
index 0000000..1f64c5f
--- /dev/null
+++ b/src/4_n_b_strlen.c
@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+char *str = "Hello World!\n";
+
+int main () {
+	int Laenge = 0;
+	char * str_pointer = str;
+
+	while (*str_pointer++ != '\0' ) {
+		++Laenge;
+	}
+
+	printf("%d: %s", Laenge, str);
+
+	return 0;
+}
diff --git a/src/4_p_a_swap.c b/src/4_p_a_swap.c
new file mode 100644
index 0000000..5421374
--- /dev/null
+++ b/src/4_p_a_swap.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+void swap(int * a, int * b);	/* function declaration */
+
+int main() {
+	int a = 4, b = 14;
+
+	swap(&a, &b);
+
+	printf("a = %d\nb = %d\n", a, b);
+
+	return 0;
+}
+
+void swap(int * a, int * b) {	/* funtion implementation */
+	int temp = *a;
+	*a = *b;
+	*b = temp;
+}
diff --git a/src/4_p_c_strings.c b/src/4_p_c_strings.c
new file mode 100644
index 0000000..9eef9f7
--- /dev/null
+++ b/src/4_p_c_strings.c
@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <string.h>
+
+#define MAX_LENGTH 81 /* 80 characters + '\0' termination */
+
+int main () {
+	int i;
+	char str1[MAX_LENGTH]; /* Eingabestring */
+	char str2[MAX_LENGTH]; /* Ausgabestring */
+	char *p1, *p2;
+
+	printf("Bitte ein Wort eingeben: ");
+	scanf(" %s", str1);
+
+	/* soll nur eine Ausgabe erfolgen, geht dies auch ohne str2 und zwar wie folgt: */
+	printf("So soll das Ergebnis aussehen: ");
+
+	for (i = strlen(str1) - 1; i>=0; i--) {
+		printf("%c", str1[i]);
+	}
+
+	/* nun mit Kopie in str2: */
+	p1 = str1 + strlen(str1) -1; /* p1 zeigt auf das Ende von str1 */
+	p2 = str2; /* p2 zeigt auf den Anfang von str2 */
+
+	/* von hinten nach vorn wird str1 zeichenweise nach str2 kopiert */
+	while (p1 >= str1) {
+		*p2++ = *p1--;
+	}
+	*p2 = '\0'; /* str2 Sting-Endezeichen abschliessen */
+
+	/* Ausgabe beider Strings */
+	printf("\n%s <--> %s\n", str1, str2);
+
+	return 0;
+}
+