Write a LEX program that reads input file and writes valid tokens to output file.

Code:

%{

%}

%%

#.*> {fprintf(yyout,"Valid Header File: %s\n",yytext);}

(printf|scanf|if|else|while|do|break|continue|int|double|float|return|char|case|char|sizeof|

long|short|typedef|switch|unsigned|void|static|struct|goto) {fprintf(yyout,"Valid

Keyword: %s\n",yytext);}

(\+|\-|\*|\/|\=|\%|\>|\<) {fprintf(yyout,"Valid Operator: %s\n",yytext);}

[0-9]+\.?[0-9]+ { fprintf(yyout,"Valid Constant: %s\n",yytext);}

[a-zA-Z]+[0-9]* { fprintf(yyout,"Valid Identifier: %s\n",yytext);}

[\"].*[\"] { fprintf(yyout,"Valid Literal: %s\n",yytext);}

(\(|\)|\{|\}|\;|\,|\&) { fprintf(yyout,"Valid Special Symbols: %s\n",yytext);}

%%

main()

{

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

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

yylex();

}

int yywrap()

{

return 1;