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  1. Code:
  2. %{
  3. #include <stdio.h>
  4. #include <stdlib.h>
  5. #include <math.h>
  6. int operation = 0;
  7. float operand1 = 0, operand2 = 0;
  8. void processOperand();
  9. %}
  10. digit [0-9]+(\.[0-9]+)?
  11. addition "+"
  12. subtraction "-"
  13. multiplication "*"
  14. division "/"
  15. power "\^"
  16. line_break \n
  17. %%
  18. {digit} { processOperand(); }
  19. {addition} { operation = 1; }
  20. {subtraction} { operation = 2; }
  21. {multiplication} { operation = 3; }
  22. {division} { operation = 4; }
  23. {power} { operation = 5; }
  24. {line_break} {
  25.  printf("The Answer: %f\n", operand1);
  26.  // Reset operands and operation after each calculation
  27.  operand1 = 0;
  28.  operand2 = 0;
  29.  operation = 0;
  30. }
  31. .|\t|\r { /* Ignore invalid characters */ }
  32. %%
  33. void processOperand() {
  34.  if (operation == 0) {
  35.  operand1 = atof(yytext);
  36. } else {
  37.  operand2 = atof(yytext);
  38.  switch (operation) {
  39.  case 1:
  40.  operand1 += operand2;
  41.  break;
  42.  case 2:
  43.  operand1 -= operand2;
  44.  break;
  45.  case 3:
  46.  operand1 *= operand2;
  47.  break;
  48.  case 4:
  49.  if (operand2 != 0) {
  50.  operand1 /= operand2;
  51.  } else {
  52.  printf("Error: Division by zero!\n");
  53.  operand1 = 0;
  54.  }
  55.  break;
  56.  case 5:
  57.  operand1 = pow(operand1, operand2);
  58.  break;
  59.  default:
  60.  printf("Invalid operation.\n");
  61.  }
  62.  operation = 0;
  63.  }
  64. }
  65. int main() {
  66.  yylex();
  67.  return 0;
  68. }
  69. int yywrap() {
  70.  return 1;
  71. }
Success #stdin #stdout #stderr 0.03s 6840KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
ERROR: /home/cj5WvF/prog:71:0: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/1X5ZtY
language:
Prolog (swi 7.6.4)
created:
10 days ago
visibility:
public

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