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  1. %{
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4.  
  5. int a[] = {0, 0, 0, 0}, i, valid = 1, opnd = 0;
  6.  
  7. void ext() {
  8.     printf("Invalid Expression\n");
  9.     exit(0);
  10. }
  11. %}
  12.  
  13. %x OPER
  14. %%
  15.  
  16. [0-9]+        { BEGIN OPER; opnd++; }
  17. <OPER>"+"     { if(valid) { valid = 0; i = 0; } else ext(); }
  18. <OPER>"-"     { if(valid) { valid = 0; i = 1; } else ext(); }
  19. <OPER>"*"     { if(valid) { valid = 0; i = 2; } else ext(); }
  20. <OPER>"/"     { if(valid) { valid = 0; i = 3; } else ext(); }
  21. <OPER>[a-zA-Z0-9]+ { 
  22.     opnd++;
  23.     if(valid == 0) {
  24.         valid = 1; 
  25.         a[i]++;
  26.     } else {
  27.         ext();
  28.     }
  29. }
  30. <OPER>"\n"    { if(valid == 0) ext(); else return 0; }
  31. .             { ext(); }
  32.  
  33. %%
  34.  
  35. int main() {
  36.     printf("Type the arithmetic expression:\n");
  37.     yylex();
  38.  
  39.     printf("Valid Arithmetic Expression\n");
  40.     printf("No. of Operands/Identifiers: %d\n", opnd);
  41.     printf("No. of Additions: %d\nNo. of Subtractions: %d\n", a[0], a[1]);
  42.     printf("No. of Multiplications: %d\nNo. of Divisions: %d\n", a[2], a[3]);
  43.  
  44.     return 0;
  45. }
  46.  
Success #stdin #stdout #stderr 0.03s 6856KB
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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/YR9Uy9/prog:2:1: Syntax error: Operator expected
ERROR: /home/YR9Uy9/prog:45:1: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/dHqXT4
language:
Prolog (swi 7.6.4)
created:
10 days ago
visibility:
public

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