cal.y

来自「lex files for given decription used as 」· Y 代码 · 共 132 行

%{

 

#include <stdio.h>

#include <math.h>
#define YYSTYPE double





extern int yylex(void);



%}




%token NUMBER

%token LAST

%left '+' '-'

%left '*' '/'

%left '^'

%left NEGATIVE

%left COS EXP SIN SQRT TAN




%%



list:

    |    list '\n'

    |    list expr '\n'           { printf("%.8g\n",(double)$2);

}

    ; 



    expr:     term                 { $$ = $1;         }

    |     expr '+' expr            { $$ = $1 + $3;    }

    |     expr '-' expr            { $$ = $1 - $3;    }

    |     expr '*' expr            { $$ = $1 * $3;    }

    |     expr '/' expr            { $$ = $1 / $3;    }

    |     expr '^' expr            { $$ = pow($1,$3); }

    |     '-' expr  %prec NEGATIVE { $$ = - $2;       }

    |     COS   term               { $2=$2*3.14159265;$2=$2/180;$$ = cos($2);    }

    |     EXP   term               {$$ = exp($2);    }

    |     SIN   term               { $2=$2*3.14159265;$2=$2/180;$$ = sin($2);    }

    |     SQRT  term               { $$ = sqrt($2);   }

    |     TAN   term               { $2=$2*3.14159265;$2=$2/180;$$ = tan($2);    }

    ;


term:     NUMBER                   { $$ = $1;         }


    |     '(' expr ')'             { $$ = $2;         }

    ;

%%



#include <stdlib.h>

#include <string.h>

#include <unistd.h>







int yyerror(const char *s)

{

    printf("\nError Occured\n");

    return 0;

}

int yywrap(void)
{
	return 1;
}

main()

{

	yyparse();

	return 0;

}