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  1. %{
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5.  
  6. #define MAX 1000
  7.  
  8. char identifiers[MAX][50];
  9. int id_count = 0;
  10.  
  11. char operators[MAX][5];
  12. int op_count = 0;
  13.  
  14. // Function to check if identifier/operator already stored
  15. int is_present(char arr[][50], int count, char* token) {
  16.     for (int i=0; i<count; i++) {
  17.         if (strcmp(arr[i], token) == 0)
  18.             return 1;
  19.     }
  20.     return 0;
  21. }
  22. %}
  23.  
  24. %%
  25.  
  26. [ \t\n]+           ;  // ignore whitespace
  27.  
  28. [a-zA-Z_][a-zA-Z0-9_]* {
  29.     if (!is_present(identifiers, id_count, yytext)) {
  30.         strcpy(identifiers[id_count++], yytext);
  31.     }
  32. }
  33.  
  34. [+\-*/=()] {
  35.     if (!is_present(operators, op_count, yytext)) {
  36.         strcpy(operators[op_count++], yytext);
  37.     }
  38. }
  39.  
  40. [0-9]+(\.[0-9]+)?   ; // ignore numbers
  41.  
  42. .   { printf("Invalid character: %s\n", yytext); exit(1); }
  43.  
  44. %%
  45.  
  46. int main() {
  47.     printf("Enter an arithmetic expression:\n");
  48.     yylex();
  49.  
  50.     printf("\nIdentifiers found:\n");
  51.     for (int i=0; i<id_count; i++) {
  52.         printf("%s\n", identifiers[i]);
  53.     }
  54.  
  55.     printf("\nOperators found:\n");
  56.     for (int i=0; i<op_count; i++) {
  57.         printf("%s\n", operators[i]);
  58.     }
  59.  
  60.     return 0;
  61. }
  62.  
Success #stdin #stdout #stderr 0.02s 7024KB
comments (?)
stdin 
a = b + 5 * c
stdout 
Standard output is empty
stderr 
ERROR: /home/jhOwYs/prog:2:1: Syntax error: Operator expected
ERROR: /home/jhOwYs/prog:61:1: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/JOcxCR
language:
Prolog (swi 7.6.4)
created:
4 days ago
visibility:
public

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