(flex.info)Whenever flex can not match the input it says "flex scanner jammed".

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Whenever flex can not match the input it says "flex scanner jammed".
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You need to add a rule that matches the otherwise-unmatched text, e.g.,

     %option yylineno
     %%
     [[a bunch of rules here]]
     
     .	printf("bad input character '%s' at line %d\n", yytext, yylineno);

   See '%option default' for more information.