%{
#include <stdio.h>
#include <string.h>

char key[100][100], head[100][100], dig[100][100], op[100][100], id[100][100];
int i = 0, j = 0, k = 0, a = 0, b = 0, c = 0, d = 0, m = 0, n = 0;
%}

/* Define Regular Expressions */
KW   "int"|"while"|"if"|"else"|"for"|"char"|"float"|"case"|"switch"
HF   "#include<".*">"
OP   "+"|"-"|"*"|"/"|"="
DIG  [0-9]*|[0-9]*"."[0-9]+
ID   [a-zA-Z][a-zA-Z0-9]*

%%

/* Pattern Matching Rules */
{KW}    { strcpy(key[i], yytext); i++; }
{HF}    { strcpy(head[j], yytext); j++; }
{DIG}   { strcpy(dig[k], yytext); k++; }
{OP}    { strcpy(op[m], yytext); m++; }
{ID}    { strcpy(id[n], yytext); n++; }
.       { /* Ignore other characters */ }

%%

/* Main Function */
int main() {
    yyin = fopen("input.c", "r+");
    yylex();

    printf("\nThe keywords are:");
    for (a = 0; a < i; a++) {
        printf("\n%s", key[a]);
    }

    printf("\nThe header files are:");
    for (b = 0; b < j; b++) {
        printf("\n%s", head[b]);
    }

    printf("\nThe digits are:");
    for (c = 0; c < k; c++) {
        printf("\n%s", dig[c]);
    }

    printf("\nThe operators are:");
    for (d = 0; d < m; d++) {
        printf("\n%s", op[d]);
    }

    printf("\nThe identifiers are:");
    for (d = 0; d < n; d++) {
        printf("\n%s", id[d]);
    }

    return 0;
}

/* Function to Handle End of File */
int yywrap() {
    return 1;
}