Write a LEX program that reads input from input file and write backs same content by replacing printf by write and scanf by read keyword in output file.

%{

#include<stdio.h>

#include<string.h>

%}

%%

"printf" {fprintf(yyout,"write",yytext);}

"scanf" {fprintf(yyout,"read",yytext);}

. ; {fprintf(yyout,"%s",yytext);} 

%%

main()

{

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

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

yylex();

}

int yywrap()

{

return(1);

}