lex,yacc program for stack (has bugs) - current code

stack.l

%{
    #include "y.tab.h"
    //extern char * yytext
%}
%%
[0-9]+ {return digit;}
[a-z]+ {return id;}
[\t] ;
[\n] {return 0;}
. {return yytext[0];}
%%
/*int yywrap()
{
  return 1;
}*/

stack.y

%{
#include <stdio.h>
#include <ctype.h>
#include <string.h>
int yylex();
void push();
void pop();
void pop2();
void pop3();
void yyerror();
%}
%token id digit
%left '+''-'
%left '*''/'
%right '^'
%right '='
%nonassoc UMINUS
%%
S:id {push();}'='E {pop();}
E:E'+' {push();}T {pop3();}
|E'-'{push();}T {pop3();}
|T
;
T:T'*' {push();}'='F {pop3();}
|T'/' {push();}F {pop3();}
|E'^'{push();}F {pop3();}
|F
;
F:id {push();}
|digit {push();}
|'('E')'
|'-'{push();}F {pop2();} %prec UMINUS
;
%%
char stack[10];
//char **stack;
char var[10],temp[10];
int top=0;
char i='0';
int main()
{
  yyparse();
  yylex();
  return 0;
}

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

void push(){
  top++;
  printf("\n%c",yytext);
  //strcpy(stack[top],yytext[0]);
}
void pop3()
{
  printf("\n%c=%s%s%s",i,stack[top-2],stack[top-1],stack[top]);
  top = top-2;
  temp[0]=i;
  strcpy(var,"t");
  strcat(var,temp);
  strcpy(stack[top],var);
  i++;
}
void pop()
{
  printf("\n%s=%s\n", stack[top-1],stack[top]);
}
void pop2()
{
  printf("\n%c=%s%s",i,stack[top-1],stack[top]);
  top--;
  temp[0]=i;
  strcpy(var,"t");
  strcat(var,temp);
  strcpy(stack[top],var);
  i++;
}