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  1. /*lex code to determine whether input is an identifier or not*/
  2. % {
  3. #include <stdio.h>
  4.     %
  5. }
  6.  
  7.     / rule section % %
  8.     // regex for valid identifiers
  9.     ^[a - z A - Z _][a - z A - Z 0 - 9 _] * printf("Valid Identifier");
  10.  
  11. // regex for invalid identifiers
  12. ^[^a - z A - Z _] printf("Invalid Identifier");
  13. .;
  14. % %
  15.  
  16.     main()
  17. {
  18.     yylex();
  19. }
Success #stdin #stdout #stderr 0.02s 6968KB
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stdin
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Standard input is empty
stdout
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Standard output is empty
stderr
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ERROR: /home/35gKzI/prog:19:0: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/w3ioZ1
language:
Prolog (swi 7.6.4)
created:
1 year ago
visibility:
public

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