A addition compiler (adyacc.y)

% {#include int yylex (void); void Yyerror (char *);%}% token integer %% Program: program expr '/ n' {printf ("% d / n", $ 2); } |; Expr: integer {$$ = $ 1;} | expr ' ' expr {$$ = $ 1 $ 3;} | evr '-' expr {$$ = $ 1 - $ 3;}; %% void Yyerror (charr * s) {FPRINTF (stderr, "% s / n", s); return 0;} int main (void) {yyparse (); return 0;}