Merge pull request #76 from krperry/master

Fixed readme and variables.

Author: richpl

README.md

@@ -220,7 +220,7 @@ are all invalid.
 
 Numeric variables have no suffix, whereas string variables are always suffixed by '$'. Note that 'I' and 'I$' are
 considered to be separate variables. Note that string literals must always be enclosed within double quotes (not single quotes).
-Using no quotes will result in a syntax error. In addition, for floating point numbers less than one (e.g. 0.67), the decimal point must always be prefixed by a zero (e.g. .67 will be flagged as a syntax error).
+Using no quotes will result in a syntax error. 
 
 Array variables are defined using the **DIM** statement, which explicitly lists how
 many dimensions the array has, and the sizes of those dimensions:

basicparser.py

@@ -1025,9 +1025,14 @@ def __factor(self):
                 self.__operand_stack.append(self.__sign*self.__symbol_table[self.__token.lexeme])
 
             else:
-                raise RuntimeError('Name ' + self.__token.lexeme + ' is not defined' +
-                                   ' in line ' + str(self.__line_number))
-
+                # default variables values for undefined variables.
+                if self.__token.lexeme.endswith ("$"):
+                    # default string
+                    self.__operand_stack.append("")
+                else:
+                    #default int
+                    self.__operand_stack.append(0)
+            
             self.__advance()
 
         elif self.__token.category == Token.LEFTPAREN: