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  1. alpha [A-Za-z]
  2. digit [0-9]
  3. %%
  4. [ \t\n]   
  5. if    return IF;
  6. then    return THEN;
  7. else    return ELSE;
  8. {digit}+    return NUM;
  9. {alpha}({alpha}|{digit})*    return ID;
  10. "<="    return LE;
  11. ">="    return GE;
  12. "=="    return EQ;
  13. "!="    return NE;
  14. "||"    return OR;
  15. "&&"    return AND;
  16. .    return yytext[0];
  17. %%
  18.  
  19.  
  20. %{
  21. #include <stdio.h>
  22. #include <stdlib.h>
  23. %}
  24. %token ID NUM IF THEN LE GE EQ NE OR AND ELSE
  25. %right '='
  26. %left AND OR
  27. %left '<' '>' LE GE EQ NE
  28. %left '+''-'
  29. %left '*''/'
  30. %right UMINUS
  31. %left '!'
  32. %%
  33.  
  34. S      : ST {printf("Input accepted.\n");exit(0);};
  35. ST    : IF '(' E2 ')' THEN ST1';' ELSE ST1';'
  36.         | IF '(' E2 ')' THEN ST1';'
  37.         ;
  38. ST1  : ST
  39.         | E
  40.         ;
  41. E    : ID'='E
  42.       | E'+'E
  43.       | E'-'E
  44.       | E'*'E
  45.       | E'/'E
  46.       | E'<'E
  47.       | E'>'E
  48.       | E LE E
  49.       | E GE E
  50.       | E EQ E
  51.       | E NE E
  52.       | E OR E
  53.       | E AND E
  54.       | ID
  55.       | NUM
  56.       ;
  57. E2  : E'<'E
  58.       | E'>'E
  59.       | E LE E
  60.       | E GE E
  61.       | E EQ E
  62.       | E NE E
  63.       | E OR E
  64.       | E AND E
  65.       | ID
  66.       | NUM
  67.       ;
  68.  
  69. %%
  70.  
  71.  
  72. main()
  73. {
  74.   printf("Enter the exp: ");
  75.   yyparse();
  76. }
Not running #stdin #stdout 0s 0KB
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if(a==1)  then b=1; else b=2;
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Standard output is empty
https://ideone.com/oWCH1j
language:
Text (text 6.10)
created:
6 years ago
visibility:
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