To speed things up, one easy step is to precompile the (static) pattern using the qr// operator, like qr/^\d{10}$/, or using the m//o flag, as in 
die unless /^\d{10}$/o;

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Also, the print statement might prove too expensive; perhaps, syswrite() is a better choice -- if you must write to output.

In reply to Re: Determining uniqueness in a string. by ioannis
in thread Determining uniqueness in a string. by Yzzyx

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