Errors

Question

1. How to differentiate between Lexical, semantic and syntax error from a given code snippet.
2. Why is this lexical error and not syntax error? 
   $ y = 0x5i; $

Comments

ref here: How is this lexical error

Answer 1

This number is start with 0 and we know octal no is start with 0 and (0 to 7 numbers are only allowed here) but here x,i written that's why it shown error in Lexical phase. It's not indentifying as Token.

Comments

0x denotes hexadecimal, so the number is not octal. Anyways I have changed variable name to avoid confusion.

Answer 2

For a lexical analyzer when it encounters 0x it thinks of the token as a hexadecimal number
But as it scans, it finds "i" and there is no space or delimiter between 0x5 and i.
Maximal Munch thus invalidates the token.

Note : Event though whitespace is removed by lexical analyzer and is not passed to parser it still needs it as a delimiter