# Activity Goals

The goals of this activity are:
1. To define a lexeme and to define tokens based on lexemes
2. To differentiate between types, reserved words, and identifiers in a scanner
3. To read a file and identify defined tokens

# The Activity

## Model 1: Scanning Lexemes for Tokens with flex

### Questions

1. What is a lexeme? What is a token?
2. Describe an algorithm to read a String from left to right, returning tokens as they are identified. What familiar programming construct or paradigm do you see (hint - look at the loop, conditional, and check for the current character!)?
3. How would you modify this scanner configuration to support an assignment operator and an identifier (variable) token?
4. Notice the actual text of the token is not typically returned directly by the scanner. Rather, it is stored in a variable (here, yylval). What is returned instead, and why not simply return yytext directly?
5. Sketch the symbol table for the lexemes above. For each token type, assign a constant value to the type, and describe the type and format of the resulting token value.

## Submission

I encourage you to submit your answers to the questions (and ask your own questions!) using the Class Activity Questions discussion board. You may also respond to questions or comments made by others, or ask follow-up questions there. Answer any reflective prompt questions in the Reflective Journal section of your OneNote Classroom personal section. You can find the link to the class notebook on the syllabus.