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  1. %{
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <math.h>
  5.  
  6. int op = 0;
  7. float a, b;
  8. %}
  9.  
  10. %option noyywrap
  11.  
  12. /* Regular Expressions Section */
  13. dig [0-9]+(\.[0-9]+)?   /* Match numbers including decimals */
  14. add "+"                 /* Match addition operator */
  15. sub "-"                 /* Match subtraction operator */
  16. mul "*"                 /* Match multiplication operator */
  17. div "/"                 /* Match division operator */
  18. pow "^"                 /* Match exponentiation operator */
  19. ln \n                   /* Match newline to print result */
  20.  
  21. /* Rules Section */
  22. %%
  23. {dig} {digi();}           /* Process numbers */
  24. {add} {op=1;}             /* Set operation to addition */
  25. {sub} {op=2;}             /* Set operation to subtraction */
  26. {mul} {op=3;}             /* Set operation to multiplication */
  27. {div} {op=4;}             /* Set operation to division */
  28. {pow} {op=5;}             /* Set operation to exponentiation */
  29. {ln} {printf("\nThe Answer: %f\n\n", a);}  /* Print result on new line */
  30.  
  31. /* C Code Section */
  32. %%
  33.  
  34. void digi() {
  35.     if (op == 0) {
  36.         a = atof(yytext);  // Convert the first number to float
  37.     } else {
  38.         b = atof(yytext);  // Convert the second number to float
  39.         switch (op) {
  40.             case 1: a = a + b; break;   // Addition
  41.             case 2: a = a - b; break;   // Subtraction
  42.             case 3: a = a * b; break;   // Multiplication
  43.             case 4: 
  44.                 if (b == 0) {
  45.                     printf("Error: Division by zero\n");
  46.                     exit(1);  // Exit on division by zero
  47.                 }
  48.                 a = a / b; break;   // Division
  49.             case 5: a = pow(a, b); break;  // Exponentiation
  50.         }
  51.         op = 0; // Reset the operation after executing
  52.     }
  53. }
  54.  
  55. int main(int argc, char *argv[]) {
  56.     yylex();  // Call Lex to start scanning
  57.     return 0;
  58. }
  59.  
  60. int yywrap() {
  61.     return 1;  // Indicates end of input for Lex
  62. }
  63.  
Success #stdin #stdout #stderr 0.03s 6944KB
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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/Q1SVui/prog:62:1: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/X4wffl
language:
Prolog (swi 7.6.4)
created:
317 days ago
visibility:
public

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