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  1. %{
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4.  
  5. int COMMENT = 0;   // Flag to track multi-line comments
  6. %}
  7.  
  8. identifier [a-zA-Z][a-zA-Z0-9]*
  9.  
  10. %%
  11.  
  12. #.*                                     { printf("\n%s is a PREPROCESSOR DIRECTIVE", yytext); }
  13.  
  14. (int|float|char|double|while|for|struct|typedef|do|if|break|continue|void|switch|return|else|goto)
  15.                                         { printf("\n%s is a KEYWORD", yytext); }
  16.  
  17. "/*"                                    { COMMENT = 1; printf("\n%s is a COMMENT", yytext); }
  18. "*/"                                    { COMMENT = 0; printf("\n%s ends COMMENT", yytext); }
  19.  
  20. {identifier}\(                          { if(!COMMENT) printf("\n%s FUNCTION", yytext); }
  21.  
  22. {identifier}(\[[0-9]*\])?               { if(!COMMENT) printf("\n%s IDENTIFIER", yytext); }
  23.  
  24. \{                                      { if(!COMMENT) printf("\n%s BLOCK BEGINS", yytext); }
  25. \}                                      { if(!COMMENT) printf("\n%s BLOCK ENDS", yytext); }
  26.  
  27. \;                                      { if(!COMMENT) printf("\n%s PUNCTUATOR", yytext); }
  28.  
  29. \".*\"                                  { if(!COMMENT) printf("\n%s STRING", yytext); }
  30.  
  31. [0-9]+                                   { if(!COMMENT) printf("\n%s NUMBER", yytext); }
  32.  
  33. =                                       { if(!COMMENT) printf("\n%s ASSIGNMENT OPERATOR", yytext); }
  34.  
  35. "=="|"<="|">="|"<"|">"                  { if(!COMMENT) printf("\n%s RELATIONAL OPERATOR", yytext); }
  36.  
  37. [ \t\n]+                                { /* ignore whitespace */ }
  38.  
  39. .                                       { /* ignore other characters */ }
  40.  
  41. %%
  42.  
  43. int main(int argc, char **argv) {
  44.     FILE *file = fopen("input.c", "r");   // File to analyze
  45.     if (!file) {
  46.         printf("Could not open the file\n");
  47.         exit(0);
  48.     }
  49.  
  50.     yyin = file;   // Set input for lexer
  51.     yylex();       // Start lexical analysis
  52.     printf("\nLexical Analysis Complete.\n");
  53.     return 0;
  54. }
  55.  
  56. int yywrap() {
  57.     return 1;
  58. }
  59.  
Success #stdin #stdout #stderr 0.02s 6868KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
ERROR: /home/TmiWab/prog:2:1: Syntax error: Operator expected
ERROR: /home/TmiWab/prog:58:1: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/b0uw8j
language:
Prolog (swi 7.6.4)
created:
3 days ago
visibility:
public

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