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  1. %{
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <math.h>
  5.  
  6. int op = 0, i;
  7. float a, b;
  8.  
  9. // Function prototype
  10. void digi(void);
  11. %}
  12.  
  13. dig     [0-9]+|([0-9]*)"."([0-9]+)
  14. add     \+
  15. sub     \-
  16. mul     \*
  17. div     /
  18. pow     \^
  19. ln      \n
  20. %%
  21.  
  22. {dig}   { digi(); }
  23.  
  24. {add}   { op = 1; }
  25. {sub}   { op = 2; }
  26. {mul}   { op = 3; }
  27. {div}   { op = 4; }
  28. {pow}   { op = 5; }
  29.  
  30. {ln}    { printf("\nThe result: %f\n\n", a); }
  31.  
  32. [\t ]+  { /* Ignore whitespace */ }
  33.  
  34. .       { printf("Unrecognized input: %s\n", yytext); }
  35. %%
  36.  
  37. void digi()
  38. {
  39.     if (op == 0)
  40.         a = atof(yytext);  // Convert to float
  41.     else
  42.     {
  43.         b = atof(yytext);
  44.         switch(op)
  45.         {
  46.             case 1: a = a + b; break;
  47.             case 2: a = a - b; break;
  48.             case 3: a = a * b; break;
  49.             case 4: 
  50.                 if (b != 0)
  51.                     a = a / b; 
  52.                 else
  53.                     printf("Error: Division by zero!\n");
  54.                 break;
  55.             case 5: 
  56.                 a = pow(a, b); 
  57.                 break;
  58.         }
  59.         op = 0;
  60.     }
  61. }
  62.  
  63. int main(int argc, char *argv[])
  64. {
  65.     yylex();
  66.     return 0;
  67. }
  68.  
  69. int yywrap()
  70. {
  71.     return 1;
  72. }
  73.  
  74.  
Success #stdin #stdout #stderr 0.03s 6856KB
comments (?)
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/jZK0tF/prog:2:1: Syntax error: Operator expected
ERROR: /home/jZK0tF/prog:73:0: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/2TkANy
language:
Prolog (swi 7.6.4)
created:
1 day ago
visibility:
public

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