compiler construction - What is the purpose of a lexer? -


i reading answer this question. can't seem find answer why need lexer separately

is 1 of steps program goes through during compilation? can please explain in simple terms why need lexer, , purpose serve?

a lexer take input character stream , convert tokens.

this can used variety of purposes. apply transformations lexemes simple text processing , manipulation.

or stream of lexemes can fed parser convert parser tree.

if goal compilation, lexical analysis first step. think of lower level step takes characters , converts them tokens. parser higher level mechanism alphabet consists of tokens (created lexer), parses , creates parse tree.

if goal text manipulation, manipulation rules can applied lexemes themselves.


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