lexc

#cmds

First, make sure you have Flex installed:

For installing on Ubuntu- sudo apt-get install flex

  1. Save as analyzer.l
  2. Run: flex analyzer.l
  3. Compile: gcc lex.yy.c -o analyzer -lfl
  4. Execute: ./analyzer

 


%{

#include <stdio.h>

%}


KEYWORD     auto|break|case|char|const|continue|default|do|double|else|enum|extern|float|for|goto|if|int|long|register|return|short|signed|sizeof|static|struct|switch|typedef|union|unsigned|void|volatile|while

IDENTIFIER  [a-zA-Z_][a-zA-Z0-9_]*

NUMBER      [0-9]+(\.[0-9]+)?

OPERATOR    \+|\-|\*|\/|%|==|!=|<=|>=|<|>|\=\=|\=|\&\&|\|\||\+\+|\-\-

DELIMITER   [;,\[\]\(\)\{\}]

STRING      \"([^\\\"]|\\.)*\"


%%

{KEYWORD}      { printf("Keyword\t\t=> %s\n", yytext); }

{IDENTIFIER}   { printf("Identifier\t=> %s\n", yytext); }

{NUMBER}       { printf("Number\t\t=> %s\n", yytext); }

{OPERATOR}     { printf("Operator\t=> %s\n", yytext); }

{DELIMITER}    { printf("Delimiter\t=> %s\n", yytext); }

{STRING}       { printf("String\t\t=> %s\n", yytext); }

\/\/.*         { printf("Comment\t\t=> %s\n", yytext); }

[ \t\n]+       { /* Ignore whitespace */ }

.              { printf("Unknown\t\t=> %c\n", yytext[0]); }

%%


int yywrap() {

    return 1;

}


int main() {

    printf("Enter C code (Ctrl+D to end):\n\n");

    yylex();

    return 0;

}

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