README.md

Cycle 2 — p7: Identifier Validator

Files:

• valid.l - Lexical analyzer for identifier tokens
• valid.y - Grammar rules for identifier validation

Brief description:

A Lex/Yacc (Flex/Bison) implementation of an identifier validator that checks if an input string is a valid identifier according to common programming language rules:

1. Lexical rules (valid.l):

   • Recognizes letters, digits, and underscores
   • Categorizes input into letter/digit tokens

2. Grammar rules (valid.y):

   • Enforces identifier rules:
     • Must start with a letter or underscore
     • Can be followed by letters, digits, or underscores
   • Provides clear error messages for invalid identifiers

Build and run:

flex valid.l
bison -d valid.y
gcc lex.yy.c y.tab.c -o validator
./validator

The program will prompt for an input string and indicate whether it's a valid identifier.