%
option noyywrap
 
%{
#include <stdio.h>
#include <unistd.h>
int matched = 0;
%}
 
%%
^[0-9]+$   {
              printf("%s is a number\n", yytext);
              matched = 1;
           }
 
.+         {
              printf("%s is not a number\n", yytext);
              matched = 1;
           }
 
\n         ;
%%
 
int main()
{
    yylex();
 
    /* handles empty input */
    if (!matched)
        printf(" is not a number\n");
 
    return 0;
}

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