Should I use \d or [0-9] to match digits in a Perl regex?

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It seems to me very dangerous to use \d, It is a poor design decision in the language, as in most cases you want [0-9]. Huffman-coding would dictate the use of \d for ASCII numbers.

Most of the previous posters have already highlighted why you should use [0-9], so let me give you a bit more data:

  • If I read the unicode charts correctly ‘۷۰‘ is a number (70 in indic, don’t take my word for it).

  • Try this: 

    $ perl -le '$one = chr 0xFF11; print "$one + 1 = ", $one+1;'
１ + 1 = 1

  • Here is a partial list of valid numbers (which may or may not show up properly in your browser, depending on the fonts you use), for each number, only the first of those being interpreted as a number when doing arithmetics with Perl, as shown above:

     ZERO:  0٠۰߀०০੦૦୦௦౦೦൦๐໐０
 ONE:   1١۱߁१১੧૧୧௧౧೧൧๑໑１
 TWO:   2٢۲߂२২੨૨୨௨౨೨൨๒໒２
 THREE: 3٣۳߃३৩੩૩୩௩౩೩൩๓໓３
 FOUR:  4٤۴߄४৪੪૪୪௪౪೪൪๔໔４
 FIVE:  5٥۵߅५৫੫૫୫௫౫೫൫๕໕５
 SIX:   6٦۶߆६৬੬૬୬௬౬೬൬๖໖６
 SEVEN: 7٧۷߇७৭੭૭୭௭౭೭൭๗໗７
 EIGHT: 8٨۸߈८৮੮૮୮௮౮೮൮๘໘８
 NINE:  9٩۹߉९৯੯૯୯௯౯೯൯๙໙９��

Are you still not convinced?

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