PHP is numeric or preg match 0-9 validation

Question

This isn t a big issue for me  as far as I m aware   it s more of something that s interested me  But what is the main difference  if any  of using is numeric over preg match  or vice versa  to validate user input values   Example One    lt  php      id     GET  id        if   preg match     0-9        id                Error       else              Continue         gt    Example Two    lt  php      id     GET  id        if   is numeric  id                Error       else              Continue         gt    I assume both do exactly the same but is there any specific differences which could cause problems later somehow  Is there a  best way  or something I m not seeing which makes them different

User · Answer

Meanwhile  all the values above will only restrict the values to integer   so i use     1-9  0-9    0 15      to allow float values too

User · Answer

Not exactly the same   From the PHP docs of is numeric    42  is numeric  1337  is numeric  1e4  is numeric  not numeric  is NOT numeric  Array  is NOT numeric  9 1  is numeric   With your regex you only check for  basic  numeric values   Also is numeric   should be faster

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is numeric checks whether it is any sort of number  while your regex checks whether it is an integer  possibly with leading 0s  For an id  stored as an integer  it is quite likely that we will want to not have leading 0s  Following Spudley s answer  we can do      1-9  0-9       However  as Spudley notes  the resulting string may be too large to be stored as a 32-bit or 64-bit integer value  The maximum value of an signed 32-bit integer is 2 147 483 647  10 digits   and the maximum value of an signed 64-bit integer is 9 223 372 036 854 775 807  19 digits   However  many 10 and 19 digit integers are larger than the maximum 32-bit and 64-bit integers respectively  A simple regex-only solution would be      1-9  0-9  0-8       or     1-9  0-9  0-17      respectively  but these  solutions  unhappily restrict each to 9 and 19 digit integers  hardly a satisfying result  A better solution might be something like     expr       1-9  0-9       if  preg match  expr   id   amp  amp  filter var  id  FILTER VALIDATE INT         echo  ok     else       echo  nok

User · Answer

If you re only checking if it s a number  is numeric   is much much better here  It s more readable and a bit quicker than regex   The issue with your regex here is that it won t allow decimal values  so essentially you ve just written is int   in regex  Regular expressions should only be used when there is a non-standard data format in your input  PHP has plenty of built in validation functions  even an email validator without regex

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is numeric checks more      Finds whether the given variable is numeric  Numeric strings consist   of optional sign  any number of digits  optional decimal part and   optional exponential part  Thus  0123 45e6 is a valid numeric value    Hexadecimal notation  0xFF  is allowed too but only without sign    decimal and exponential part

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is numeric would accept  -0 5e 12  as a valid ID

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According to http   www php net manual en function is-numeric php  is numeric alows something like   0123 45e6  or  0xFF   I think this not what you expect   preg match can be slow  and you can have something like 0000 or 0051   I prefer using ctype digit  works only with strings  it s ok with   GET     lt  php    id     GET  id      if  ctype digit  id           echo  ok       else         echo  nok         gt

User · Answer

PHP s is numeric function allows for floats as well as integers  At the same time  the is int function is too strict if you want to validate form data  strings only   Therefore  you had usually best use regular expressions for this   Strictly speaking  integers are whole numbers positive and negative  and also including zero  Here is a regular expression for this        0    -   1-9  0-9       OR  if you want to allow leading zeros         -   0   1-9  0-9      Note that this will allow for values such as -0000  which does not cause problems in PHP  however   MySQL will also cast such values as 0    You may also want to confine the length of your integer for considerations of 32 64-bit PHP platform features and or database compatibility  For instance  to limit the length of your integer to 9 digits  excluding the optional - sign   you could use        0    -   1-9  0-9  0 8

User · Answer

You can use this code for number validation   if   preg match     0-9    i    phone              errorMSG    Invalid Number             error      1

User · Answer

is numeric   allows any form of number  so 1  3 14159265  2 71828e10 are all  numeric   while your regex boils down to the equivalent of is int

User · Answer

is numeric   tests whether a value is a number  It doesn t necessarily have to be an integer though - it could a decimal number or a number in scientific notation   The preg match   example you ve given only checks that a value contains the digits zero to nine  any number of them  and in any sequence   Note that the regular expression you ve given also isn t a perfect integer checker  the way you ve written it  It doesn t allow for negatives  it does allow for a zero-length string  ie with no digits at all  which presumably shouldn t be valid    and it allows the number to have any number of leading zeros  which again may not be the intended    EDIT   As per your comment  a better regular expression might look like this      1-9  0-9       This forces the first digit to only be between 1 and 9  so you can t have leading zeros  It also forces it to be at least one digit long  so solves the zero-length string issue   You re not worried about negatives  so that s not an issue   You might want to restrict the number of digits  because as things stand  it will allow strings that are too big to be stored as integers  To restrict this  you would change the star into a length restriction like so      1-9  0-9  0 15      This would allow the string to be between 1 and 16 digits long  ie the first digit plus 0-15 further digits   Feel free to adjust the numbers in the curly braces to suit your own needs  If you want a fixed length string  then you only need to specify one number in the braces   Hope that helps

[php] PHP is_numeric or preg_match 0-9 validation

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