LEX Program for identifying the below and printing the identified token along with information. Keywords: int, char, double, void, main Identifier: letter(letter| digit)* Integer, Float, and Relational operators

The question seems to be asking for a LEX program that can identify certain keywords, identifiers, and operators in a given input. Here's a simple example of how you might structure this program:

%{
%}

%%

"int" { printf("Keyword: %s\n", yytext); }
"char" { printf("Keyword: %s\n", yytext); }
"double" { printf("Keyword: %s\n", yytext); }
"void" { printf("Keyword: %s\n", yytext); }
"main" { printf("Keyword: %s\n", yytext); }

[a-zA-Z][a-zA-Z0-9]* { printf("Identifier: %s\n", yytext); }

[0-9]+ { printf("Integer: %s\n", yytext); }
[0-9]+"."[0-9]+ { printf("Float: %s\n", yytext); }

"<"|"<="|">"|">="|"=="|"!=" { printf("Relational operator: %s\n", yytext); }

%%

int main(void)
{
    yylex();
    return 0;
}

This program will scan an input and print out whether each token is a keyword, an identifier, an integer, a float, or a relational operator. The regular expressions in the program define what each of these tokens looks like. For example, an identifier is defined as a letter followed by any number of letters or digits.