Write a LEX program that reads input file and copies only words starting with vowels to output file.

               Code :

%{

#include<stdio.h>

#include<string.h>

%}

alpha [a-zA-Z]

digit [0-9]

space [ \n\t]

start ^(a|e|i|o|u|A|E|I|O|U)

%%

{start}({alpha}|{digit})* {fprintf(yyout,"%s",yytext);}

{space}(a|e|i|o|u|A|E|I|O|U)({alpha}|{digit})*  {fprintf(yyout,"%s",yytext);}

. ;

%%

main()

{

yyin=fopen("in.txt","r");

yyout=fopen("out.txt","w");

yylex();

}

int yywrap()

{

return 1;

}