diff --git a/src/c/a3.c b/src/c/a3.c
index a61f18f..d4420c8 100644
--- a/src/c/a3.c
+++ b/src/c/a3.c
@@ -1,30 +1,84 @@
 #include "a3.h"
 #include <stdlib.h>
 #include <stdio.h>
+#include <mem.h>
+#include <assert.h>
 
 void memdump(unsigned char *string) {
+    int i;
+    unsigned char *pc = string;
+    int length = strlen((const char *) string);
+    unsigned char buff[length];
 
+    for (i = 0; i < length; i++) {
+
+        if ((i % 16) == 0) {
+            if (i != 0)
+                printf("  %s\n", buff);
+            printf("  0x%04x ", i);
+        }
+
+        printf(" %02x", pc[i]);
+
+        if ((pc[i] < 0x20) || (pc[i] > 0x7e)) {
+            buff[i % 16] = '.';
+        } else {
+            buff[i % 16] = pc[i];
+        }
+
+        buff[(i % 16) + 1] = '\0';
+    }
+    while ((i % 16) != 0) {
+        printf("   ");
+        i++;
+    }
+
+    printf("  %s\n", buff);
 }
 
 
 int memreplace(char *string, char cin, char cout, char **caddr) {
-
+    return 42;
 }
 
 int main(int argc, char **argv) {
-    if(argc <= 3) {
-        printf("Not enough arguments");
+    if(argc != 4) {
+        printf("Not enough arguments or to many arguments");
         return -1;
     }
 
+    size_t size = 1;
+    for (int i = 1; i < argc; i++) {
+        size += strlen(argv[i]) + 1;
+    }
+    char *str = malloc(size);
+    if (!str) {
+        fprintf(stderr, "No memory\n");
+        return 2;
+    }
 
-    memdump((unsigned char*)argv[1]);
+    size = 0;
+    for (int i = 1; i < argc; i++) {
+
+        size += sprintf(str + size, "%s ", argv[i]);
+
+        assert(str[size] == '\0');
+    }
+
+    str[--size] = '\0';
+
+    printf("%s\n", str);
+
+
+    memdump((unsigned char*)str);
     char **lastAddress;
     int count = memreplace(argv[1], *argv[2], *argv[3], 0);
 
-    printf("Laenge der Zeichenkette (inkl \\0): %i Bytes\n", sizeof(argv[1]));
+    printf("Laenge der Zeichenkette (inkl \\0): %i Bytes\n", strlen(argv[1]));
     printf("Ersetzen: '%c' mit '%c'\n", *argv[2], *argv[3]);
     printf("Suchzeichen wurde %i mal gefunden und ersetzt\n", count);
     printf("zuletzt an Addresse 0x%lx \n", (unsigned long) (&lastAddress));
     memdump((unsigned char*)argv[1]);
+
+    free(str);
 }
\ No newline at end of file
diff --git a/src/c/a3.h b/src/c/a3.h
index 5752e0e..776856f 100644
--- a/src/c/a3.h
+++ b/src/c/a3.h
@@ -1,2 +1,7 @@
+#ifndef HnP_a3
+#define HnP_a3
+
 void mempdump(unsigned char *string);
-int memreplace(char *string, char cin, char cout, char **caddr);
\ No newline at end of file
+int memreplace(char *string, char cin, char cout, char **caddr);
+
+#endif
\ No newline at end of file