Calc project

%{
    #include <stdio.h>
    void yyerror(char *);
    int yylex(void);

    int sym[26];
%}

%token INTEGER VARIABLE
%token EXIT
%left '+' '-'
%left '*' '/'
%left '^'
%left '>' '<' GE LE EQ NE
%left COS SIN TAN SQRT EXP CTAN POW LOG


%%

program:
        program statement '\n'
        | /* NULL */
        ;

statement:
        expression                      { printf("%d\n", $1); }
        | VARIABLE '=' expression       { sym[$1] = $3; }
        ;

expression:
        INTEGER
        | VARIABLE                      { $$ = sym[$1]; }
        | expression '+' expression     { $$ = $1 + $3; }
        | expression '-' expression     { $$ = $1 - $3; }
        | expression '*' expression     { $$ = $1 * $3; }
        | expression '/' expression     { $$ = $1 / $3; }
        | '(' expression ')'            { $$ = $2; }
	| COS expression		{ $$ = printf("%.2f", cos($2)); }
	| SIN expression		{ $$ = printf("%.2f", sin($2)); }
	| TAN  expression               { printf("%.2f",tan($2));    }
        | CTAN  expression              { printf("%.2f", 1/tan($2));    }
	| expression POW expression	{ $$ = pow($1,$3);}
	| SQRT expression		{ $$ = sqrt($2);}
	| LOG expression		{ printf("%f", log($2));}
	| expression '<' expression     { ($1 < $3) ? printf("True\n"):printf("False\n"); }
        | expression '>' expression     { ($1 > $3) ? printf("True\n"):printf("False\n");}
	| expression GE expression      { ($1 >= $3) ? printf("True\n"):printf("False\n"); }
	| expression LE expression      { ($1 <= $3) ? printf("True\n"):printf("False\n"); }
	| expression EQ expression      { ($1 <= $3) ? printf("True\n"):printf("False\n"); }
	| expression NE expression      { ($1 != $3) ? printf("True\n"):printf("False\n"); }
	| EXIT {exit(0);}
        ;

%%

void yyerror(char *s) {
    fprintf(stderr, "%s\n", s);
}

int main(void) {
    yyparse();
}
//================================================================================
//LEX
    /* calculator #1 */
%{
    #include "y.tab.h"
    #include <stdlib.h>
    #include <math.h>
    void yyerror(char *);
%}

%%

"cos"   return COS;
"sin"	return SIN;
"tan"	return TAN;
"ctan"	return CTAN;
"pow"	return POW;
"sqrt"	return SQRT;
"log"	return LOG;
">="    return GE;
"<="    return LE;
"=="    return EQ;
"!="    return NE;

"exit" return EXIT;

[a-z]*       {
                yylval = *yytext - 'a';
                return VARIABLE;
                }

[1-9][0-9]*      {
			 yylval = atoi(yytext);
			 return INTEGER;
		 }

[-+()=/*\n<>]     { return *yytext; }

[ \t\n]   ;       /* skip whitespace */

.			yyerror("Unknown character");

%%

int yywrap(void) {
    return 1;
}