Syntax-directed translation in YACC
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Exercise 4.
Write a translator that accepts single logical expressions being bulit of: constants 'true' and 'false', variable names (sequences of small letters), 
connectives: 'and', or', 'not' and parentheses.
Every correct expression sholuld be transcribed to the output with the names of connectives set to uppercase.

For example, the input:

	a or b and (not cd or efg) or false

should be transcribed as:

	a OR b AND ( NOT cd OR efg ) OR false 

The scanner is as follows:
%{
# include <stdlib.h>
#include "ytab.h"
%}
%%
"true"			{return( true);}
"false"			{return( false);}
"and"			{return( and);}
"or"			{return( or);}
"not"			{return( not);}

[a-z][a-z]*		{
			  yylval.text=strdup(yytext);
                          return(nazwa);
                        }
"("			{ return('('); }
")"			{ return(')'); }
\ |\n			;
.			{{yyterminate();}

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Exercise 5.
Use the YACC generator to create a program to translate C-like 'for' statements to Pascal-like ones. 
The simplified syntax scheme of  c 'for' statements is as follows;

for ( 'ident' ='const1' ; 'ident' 'relop' 'const2'; 'ident' 'incdec') {}

where 'ident' is the name of a variable, 'const1', 'const2' are integer constants, 'relop' is one of : '<' '<=', '>', '>=', 'incdec' stand for increment or decrement operator.

For example:

		for (x=0;x<5;x++) {}

is translated to:

		for x:=0 to 4 do ;

while for the input:

		for (y=13;y<=0;y--) {}
the output should be as follows:

		for y:=13 downto 0 do ;

Note, that the translator should only check the context-free syntax of the input sentence!

The scanner is given below:
%{
#include <stdlib.h>
#include "ytab.h"
%}
%%
"for"			{return( forr);}
[0-9]+ 			{ yylval.ival=atoi(yytext);
			  return( number); }
"<="			{return( le);}
">="			{return( ge);}
"="			{return ('=');}
"++"			{return (incr);}
"--"			{return(decr);}
"<"			{return( '<');}
">"			{ return('>'); }
[a-z][a-z]*			{ yylval.text=strdup(yytext);
        	          		  return(nazwa);}
";"			{ return(';'); }
")"			{ return(')'); }
"{"			{return ('{');}
"}"			{return('}');}
"("			{ return('('); }
\ |\n			;
.			{yyterminate();}