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  1. /* lexical_analyzer.l */
  2. %{
  3. #include <stdio.h>
  4. #include <stdlib.h>
  5. %}
  6.  
  7. %%
  8.  
  9. "int"       { printf("Keyword: int\n"); }
  10. "float"     { printf("Keyword: float\n"); }
  11. "if"        { printf("Keyword: if\n"); }
  12. "else"      { printf("Keyword: else\n"); }
  13.  
  14. [0-9]+      { printf("Integer: %s\n", yytext); }
  15. [0-9]+\.[0-9]+  { printf("Float: %s\n", yytext); }
  16.  
  17. "="         { printf("Assignment Operator: =\n"); }
  18. "=="        { printf("Equality Operator: ==\n"); }
  19. "+"         { printf("Arithmetic Operator: +\n"); }
  20. "-"         { printf("Arithmetic Operator: -\n"); }
  21. "*"         { printf("Arithmetic Operator: *\n"); }
  22. "/"         { printf("Arithmetic Operator: /\n"); }
  23.  
  24. [ \t\n\r]+  { /* Skip whitespace */ }
  25.  
  26. .           { printf("Unknown character: %s\n", yytext); }
  27.  
  28. %%
  29.  
  30. int main(int argc, char **argv) {
  31.     if (argc > 1) {
  32.         FILE *fp = fopen(argv[1], "r");
  33.         if (!fp) {
  34.             perror("Error opening file");
  35.             return 1;
  36.         }
  37.         yyin = fp;
  38.     }
  39.     yylex(); // Start lexical analysis
  40.     return 0;
  41. }
  42.  
Success #stdin #stdout #stderr 0.02s 6948KB
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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/9hgiIu/prog:3:1: Syntax error: Operator expected
ERROR: /home/9hgiIu/prog:41:1: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/8PM9gF
language:
Prolog (swi 7.6.4)
created:
9 days ago
visibility:
public

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