Ex2 (a) 6,7

You could try shortcuts for some of these e.g. for 6c) you could just change:

	| exp add_sub term	{$$= make_operator ($1, $2, $3);}

to:

	| term add_sub exp	{$$= make_operator ($1, $2, $3);}

Alternatively, you could fully replace all the rules for exp, term and factor. It is probably simplest to always do:

%type  num

num	: number	{$$= make_operand ($1);}
	;

and use "num" everywhere the question mentions "number".

7a)

%type  exp num

exp     : num			{$$= $1;}
	| num add_sub num	{$$= make_operator ($1, $2, $3);}
	| num mul_div num	{$$= make_operator ($1, $2, $3);}
	;

which can be run as e.g.:

1;
 
 1
=1
1+2;
 
     2
 +
     1
=3
1*2;
 
     2
 *
     1
=2
1+2*3;
syntax error

7b)

%type  exp term num

exp     : term			{$$= $1;}
	| exp add_sub term	{$$= make_operator ($1, $2, $3);}
	;
term	: num			{$$= $1;}
	| term mul_div num	{$$= make_operator ($1, $2, $3);}
	;

and all the rest are very similar.