%{
#include <stdio.h>
#include <string.h>
// List of C keywords
char *keywords[] = {
"auto", "break", "case", "char", "const", "continue", "default", "do",
"double", "else", "enum", "extern", "float", "for", "goto", "if",
"int", "long", "register", "return", "short", "signed", "sizeof",
"static", "struct", "switch", "typedef", "union", "unsigned",
"void", "volatile", "while"
};
int is_keyword(char *word) {
int i;
for (i = 0; i < sizeof(keywords)/sizeof(keywords[0]); i++) {
if (strcmp(word, keywords[i]) == 0)
return 1;
}
return 0;
}
%}
%%
[a-zA-Z_][a-zA-Z0-9_]* {
if (is_keyword(yytext))
printf("Keyword: %s\n", yytext);
else
printf("Identifier: %s\n", yytext);
}
[0-9]+\.[0-9]+ { 
printf("Constant (float): %s\n", yytext); 
}
 [0-9]+ {
 printf("Constant: %s\n", yytext); 
}

"=="|"!="|"<="|">="|"&&"|"||"|"++"|"--" { 
printf("Operator: %s\n", yytext); 
}
 [+\-*/%=<>&|^~!] {
 printf("Operator: %s\n", yytext);
}

[(){}\[\],;:.?] { 
printf("Special Character: %s\n", yytext); 
}
[ \t\n]+ ; // Ignore whitespace
. {
printf("Unknown: %s\n", yytext);
}
%%
int main(int argc, char **argv) {
yylex();
return 0;
}
int yywrap() {
return 1;
}