Exit after an unknown token is found

1 files changed, 2 insertions, 0 deletions

diff --git a/lexer.l b/lexer.l
index 30606aa..6b0294f 100644
--- a/lexer.l
+++ b/lexer.l
@@ -1,5 +1,6 @@
 %option noyywrap
 %{
+#include <stdlib.h>
 #include <string.h>
 #include "symbol-table.h"
 
@@ -139,6 +140,7 @@ ERROR           .
 {ERROR}         {
                     fprintf(stderr, "%d: error: undefined character `%s'\n",
                         line_number, yytext);
+                    exit(1);
                 }