XeL DNA Ccay is a calculator again.

%{
#include "Parser.h"
%}

%%

"+" {
return PLUS;
}

"-" {
return minus;
}

"/" {
return DIV;
}

"*" {
return MULT;
}

"(" {
return l_par;
}

")" {
return r_par;
}

[0-9]+ {
Yylval = Atoi (Yytext);

return INTEGER;
}

"/n" {
return NL;
}

. ;
%%

----------------------------------------------------------------------------------------------------------- ---------------------------------------- 

%{
int tempCount1 =-1;
int tempCount2 =-1;
int tempCount3 =-1;
int tempCount4 =-1;
int tempCount5 =-1;
int tempCount6 =-1;
int tempCount7 =-1;
%}
%token PLUS
%token minus
%token DIV
%token MULT
%token L_par
%token R_par
%token INTEGER
%token NL

%%

Calc
: Calc expression NL {printf ("%d/n", $ $);}
| Expression NL {printf ("%d/n", $ $);}
;

Expression
: term {$$ = $;}
|  Expression PLUS Term {tempCount6 = $ + $; $$ = $ + $; }
| Expression minus term {tempCount7 = $-$ $; $$ = $-$;}
;

Term
: Factor {$$ = $;}
|   Term MULT Factor {tempCount4 = $ * $ $; $$ = $ * $ $; }
| Term DIV Factor {TEMPCOUNT5 =$1/$ $; $$ = $/$;}
;

Factor
: L_par expression R_par {tempCount1 = $; $$ = $;}
| INTEGER {tempCount2 = $; $$ = $;}
| Minus factor {tempCount3 =-$2; $$ =-$2;}

%%

int Yyerror (char *str) {
printf ("%s/n", str);
}

Input (4-1)

TempCount2 = 2

TempCount2 = 4

TempCount2 = 1

TEMPCOUNT7 = 3

TempCount1 = 3

TEMPCOUNT4 = 6

Read into 2→ multiplication sign →integer (factor) match

Factor (term) → Read into the left width → read into the 4→ read and subtract

INTEGER (factor) match →factor (term) →term (expression)

Read into the 1→ read into the right width →integer (factor) match →factor (term)

L_par expression r_par match →term MULT factor match →term (expression)

----------------------------------

You can define terminator and non-terminator types,

%token PLUS
%token minus
%token DIV
%token MULT
%token L_par
%token R_par
%token <value> integers
%token NL

%type <node> Calc
%type <node> Expression
%type <node> Term
%type <node> Factor

%union{
int value;
CNode *node;
};