diff --git a/assignments/PA2/cool.flex b/assignments/PA2/cool.flex
index 4a34985..c13b195 100644
--- a/assignments/PA2/cool.flex
+++ b/assignments/PA2/cool.flex
@@ -44,7 +44,6 @@ extern YYSTYPE cool_yylval;
  */
 
 int comment_nest_level;
-int string_recover_error;
 %}
 
 /*
@@ -83,7 +82,7 @@ TRUE          t[Rr][Uu][Ee]
 FALSE         f[Aa][Ll][Ss][Ee]
 
 
-%x NCOMMENT SCOMMENT STRING
+%x NCOMMENT SCOMMENT STRING STRINGREC
 
 %%
 
@@ -193,38 +192,64 @@ FALSE         f[Aa][Ll][Ss][Ee]
   *  \n \t \b \f, the result is c.
   *
   */
+<STRINGREC>\\\n   {
+                    curr_lineno += 1;
+                  }
+  /*
+    * In either case(null char | too long), lexing should resume after the end of the string.
+    * The end of the string is defined as either:
+    *   the beginning of the next line if an unescaped newline occurs after these errors are encountered
+    *   after the closing ” otherwise
+    */
+<STRINGREC>\"|\n  {
+                    BEGIN(INITIAL);
+                    if (yytext[0] == '\n') curr_lineno += 1;
+                  }
+<STRINGREC>.
+
 \"                {
                     BEGIN(STRING);
                     string_buf_ptr = string_buf; /* reset string buf ptr*/
-                    string_recover_error = 0; /* reset error flag*/
                   }
-<STRING>[^\"\\\n] {
-                    if (!string_recover_error){
-                      *string_buf_ptr = yytext[0];
-                      string_buf_ptr ++;
-                      if (string_buf_ptr >= string_buf + MAX_STR_CONST) {
-                        string_recover_error = 1; /* string too long */
-                      }
+<STRING>[^\"\\\n\0] {
+                    /* it is necessary to exclude \0 here */
+                    *string_buf_ptr = yytext[0];
+                    string_buf_ptr ++;
+                    if (string_buf_ptr > string_buf + MAX_STR_CONST) {
+                      BEGIN(STRINGREC);
+                      cool_yylval.error_msg = "String constant too long";
+                      return (ERROR);
+                      /*
+                        * When a string is too long, 
+                        * report the error as ‘‘String constant too long’’ 
+                        * in the error string in the ERROR token.
+                        */
                     }
                   }
 <STRING>\\(.|\n)  {
-                    if (!string_recover_error){
-                      /*
-                        * Within a string, a sequence ‘\c’ denotes the 
-                        *   character ‘c’, except \b \t \n \f
-                        */
-                      switch(yytext[1]) {
-                        case 'b': *string_buf_ptr = '\b'; break;
-                        case 't': *string_buf_ptr = '\t'; break;
-                        case 'n': *string_buf_ptr = '\n'; break;
-                        case 'f': *string_buf_ptr = '\f'; break;
-                        case '\n': *string_buf_ptr = '\n'; curr_lineno += 1; break;
-                        default: *string_buf_ptr = yytext[1]; break;
-                      }
-                      string_buf_ptr ++;
-                      if (string_buf_ptr >= string_buf + MAX_STR_CONST) {
-                        string_recover_error = 1; /* string too long */
-                      }
+                    if (yytext[1] == '\n') {
+                      curr_lineno += 1;
+                    }
+                    /*
+                      * Within a string, a sequence ‘\c’ denotes the 
+                      *   character ‘c’, except \b \t \n \f
+                      */
+                    switch(yytext[1]) {
+                      case 'b': *string_buf_ptr = '\b'; break;
+                      case 't': *string_buf_ptr = '\t'; break;
+                      case 'n': *string_buf_ptr = '\n'; break;
+                      case 'f': *string_buf_ptr = '\f'; break;
+                      default: *string_buf_ptr = yytext[1]; break; /* \\n is included here*/
+                    }
+                    /*
+                      * The two characters \0(0x5c30) is valid, but actually converted to '0'(0x30)
+                      * this is handled in the default branch
+                      */
+                    string_buf_ptr ++;
+                    if (string_buf_ptr > string_buf + MAX_STR_CONST) {
+                      BEGIN(STRINGREC);
+                      cool_yylval.error_msg = "String constant too long";
+                      return (ERROR);
                     }
                   }
   /*
@@ -242,52 +267,30 @@ FALSE         f[Aa][Ll][Ss][Ee]
                       */
                   }
 <STRING>\0        {
-                    string_recover_error = 2; /* null character */
+                    BEGIN(STRINGREC);
+                    cool_yylval.error_msg = "String contains null character.";
+                    return (ERROR);
+                    /*
+                      * If the string contains invalid characters (i.e., the null character),
+                      * report this as ‘‘String contains null character’’.
+                      */
                   }
-  /*
-    * In either case(null char | too long), lexing should resume after the end of the string.
-    * The end of the string is defined as either:
-    *   the beginning of the next line if an unescaped newline occurs after these errors are encountered
-    *   after the closing ” otherwise
-    */
-<STRING>\"|\n     {
+<STRING>\n        {
+                    /* the escaped case should haved been captured in the escape rule */
                     BEGIN(INITIAL);
-                    if (yytext[0] == '\n') {
-                      curr_lineno += 1;
-                    }
-                    if (!string_recover_error) {
-                      if (yytext[0] == '\"') {
-                        cool_yylval.symbol = stringtable.add_string(string_buf, string_buf_ptr - string_buf);
-                        return (STR_CONST);
-                      }
-                      else if (yytext[0] == '\n') {
-                        /* the escaped case should haved been captured in the escape rule */
-                        cool_yylval.error_msg = "Unterminated string constant";
-                        return (ERROR);
-                        /*
-                          * If a string contains an unescaped newline, 
-                          * report that error as ‘‘Unterminated string constant’’
-                          * and resume lexing at the beginning of the next line
-                          */
-                      }
-                    }
-                    else if (string_recover_error == 1) {
-                      cool_yylval.error_msg = "EOF in string constant";
-                      return (ERROR);
-                      /*
-                        * When a string is too long, 
-                        * report the error as ‘‘String constant too long’’ 
-                        * in the error string in the ERROR token.
-                        */
-                    }
-                    else if (string_recover_error == 2){
-                      cool_yylval.error_msg = "String contains null character";
-                      return (ERROR);
-                      /*
-                        * If the string contains invalid characters (i.e., the null character),
-                        * report this as ‘‘String contains null character’’.
-                        */
-                    }
+                    curr_lineno += 1;
+                    cool_yylval.error_msg = "Unterminated string constant";
+                    return (ERROR);
+                    /*
+                      * If a string contains an unescaped newline, 
+                      * report that error as ‘‘Unterminated string constant’’
+                      * and resume lexing at the beginning of the next line
+                      */
+                  }
+<STRING>\"        {
+                    BEGIN(INITIAL);
+                    cool_yylval.symbol = stringtable.add_string(string_buf, string_buf_ptr - string_buf);
+                    return (STR_CONST);
                   }
 
  /* Integer constants
diff --git a/assignments/PA2/test.cl b/assignments/PA2/test.cl
index 87f84da..5260cd9 100644
--- a/assignments/PA2/test.cl
+++ b/assignments/PA2/test.cl
@@ -95,19 +95,39 @@ class Main {
         }
     };
 };
-    -- fuc
-    >fuck > ? *)
-    (* (* (*shit
-    fuck
-    scheisse*)sdsd*)*)
-    sds
-    inttest: Int <- 0011234; inttest2: Int <- 0x011234;
---
-            trUE <= True = true < fALse FaLSE;
-            err_string "This is
-                not ok"
-            err_string "This is \  
-                also not ok"
-            ok_string "This is \
-            ok"
-            escape_string "\"\n\\n\b\f\t\K\*"
\ No newline at end of file
+*)
+class AdditionalTest {
+-- Int test
+    valid_int: Int <- 0123123;
+    invalid_int: Int <- 0x1234;
+    invalid_int2: Int <- 000_000;
+-- String test
+    valid_str: String <- "hello world!\n";
+    escape_str: String <- "\"\n\\n\b\ff\t\K\*\00";
+    err_newline_str: String <- "This is
+                not ok";
+    err_newline_str2: String <- "This is \  
+                also not ok";
+    err_newline_str3: String <- "This is \
+                tricky lineno
+                not ok";
+    ok_newline_string: String <- "This is \
+            ok";
+-- Bool test
+    valid_bool_true: Bool <- true = tRUE = trUe;
+    valid_bool_false: Bool <- false = fALsE = fALSE;
+    invalid_bool_true: Bool <- True = TRUe;
+    invalid_bool_false: Bool <- False = FALSE;
+-- Invalid character test
+    _hello: Bool <- 1 != 2 <> 3_3?;
+-- Comment test
+    hello: Type <- 0;
+-- Valid nested comment
+    (* (* feigling (* versagar
+    scheisse
+    scheisse*) verpfeif *)
+*)
+-- Invalid nested comment
+(* *) (( lost left close, Unmatched * ) expected *)
+(* (* lost right close, EOF in comment expected) *)
+};
\ No newline at end of file
diff --git a/assignments/PA2/test_special1.cl b/assignments/PA2/test_special1.cl
new file mode 100644
index 0000000..77eeb13
--- /dev/null
+++ b/assignments/PA2/test_special1.cl
@@ -0,0 +1,2 @@
+-- String EOF
+"haha
\ No newline at end of file
diff --git a/assignments/PA2/test_special2.cl b/assignments/PA2/test_special2.cl
new file mode 100644
index 0000000..26d510b
--- /dev/null
+++ b/assignments/PA2/test_special2.cl
@@ -0,0 +1 @@
+-- Single line comment EOF
\ No newline at end of file
diff --git a/assignments/PA2/test_special3.cl b/assignments/PA2/test_special3.cl
new file mode 100644
index 0000000..ddf4885
Binary files /dev/null and b/assignments/PA2/test_special3.cl differ
diff --git a/assignments/PA2/test_special4.cl b/assignments/PA2/test_special4.cl
new file mode 100644
index 0000000..9503be1
--- /dev/null
+++ b/assignments/PA2/test_special4.cl
@@ -0,0 +1,206 @@
+(*
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+Long comment test
+*)
+long_string: String <- " long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string";
+
+long_string_resume: String <- " long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string
+long string long string long string long string long string long string long string long string long string long string";
+
+long_string_1026: String <- " long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long strin   ";
+
+long_string_1025: String <- " long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long strin  ";
+
+long_string_1024: String <- " long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long string long string long string long string long string \
+long string long string long string long string long string long strin ";
+