Regular Expression for alphanumeric and underscores

Question

I would like to have a regular expression that checks if a string contains only upper and lowercase letters  numbers  and underscores

User · Answer

In Computer Science  an Alphanumeric value often means the first character is not a number but is an alphabet or underscore  Thereafter the character can be 0-9  A-Z  a-z  or underscore       Here is how you would do that   Tested under php    regex       A-Za-z   A-Za-z d         or take this    A-Za-z   A-Za-z d       and place it in your development language

User · Answer

For me there was an issue in that I want to distinguish between alpha  numeric and alpha numeric  so to ensure an alphanumeric string contains at least one alpha and at least one numeric  I used        a-zA-Z   1   d 1       d 1   a-zA-Z   1

User · Answer

Here is the regex for what you want with a quantifier to specify at least 1 character and no more than 255 characters    a-zA-Z0-9    1 255

User · Answer

How about      A-Za-z   0-9            if you want to be explicit  or     w        if you prefer concise  Perl syntax

User · Answer

In Computer Science  an Alphanumeric value often means the first character is not a number but is an alphabet or underscore  Thereafter the character can be 0-9  A-Z  a-z  or underscore       Here is how you would do that   Tested under php    regex       A-Za-z   A-Za-z d         or take this    A-Za-z   A-Za-z d       and place it in your development language

User · Answer

The following regex matches alphanumeric characters and underscore      a-zA-Z0-9       For example  in Perl      usr bin perl -w  my  arg1    ARGV 0      check that the string contains  only  one or more alphanumeric chars or underscores if   arg1       a-zA-Z0-9           print  Failed  n     else       print  Success  n

User · Answer

Um   question   Does it need to have at least one character or no   Can it be an empty string     A-Za-z0-9       Will do at least one upper or lower case alphanumeric or underscore   If it can be zero length  then just substitute the   for      A-Za-z0-9       Edit   If diacritics need to be included  such as cedilla -   231   then you would need to use the word character which does the same as the above  but includes the diacritic characters     w     Or    w

User · Answer

I believe you are not taking Latin and Unicode characters in your matches  For example  if you need to take      or      chars  the use of   w  won t work   You can  alternatively  use this approach     A-Z  -  a-z  -  0-9       Hope it helps

User · Answer

To check the entire string and not allow empty strings  try    A-Za-z0-9

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Required Format Allow these 3   0142171547295 014-2171547295 123abc  Don t Allow other formats  validatePnrAndTicketNumber        let alphaNumericRegex    a-zA-Z0-9          let numericRegex    0-9          let numericdashRegex      1-9  3   -   0-9  10          this currBookingRefValue   this requestForm controls  quot bookingReference quot   value     if this currBookingRefValue length    14  amp  amp  this currBookingRefValue match numericdashRegex         this requestForm controls  quot bookingReference quot   setErrors   pattern   false        else if this currBookingRefValue length   6  amp  amp  this currBookingRefValue match alphaNumericRegex        this requestForm controls  quot bookingReference quot   setErrors   pattern   false        else if this currBookingRefValue length   13  amp  amp  this currBookingRefValue match numericRegex         this requestForm controls  quot bookingReference quot   setErrors   pattern   false        else      this requestForm controls  quot bookingReference quot   setErrors   pattern   true             lt input name  quot booking reference quot  type  quot text quot   class input-not-empty   quot bookingRef value quot      class  quot glyph-input form-control floating-label-input quot  id  quot bookings bookingReference quot      value  quot  quot  maxlength  quot 14 quot  aria-required  quot true quot  role  quot textbox quot   bookingRef     formControlName  quot bookingReference quot   focus   quot resetMessageField   quot   blur   quot validatePnrAndTicketNumber   quot   gt

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Try these multi-lingual extensions I have made for string    IsAlphaNumeric - String must contain atleast 1 alpha  letter in Unicode range  specified in charSet  and atleast 1 number  specified in numSet   Also  the string should comprise only of alpha and numbers   IsAlpha - String should contain atleast 1 alpha  in the language charSet specified  and comprise only of alpha   IsNumeric - String should contain atleast 1 number  in the language numSet specified  and comprise only of numbers   The charSet numSet range for the desired language can be specified  The Unicode ranges are available on below link   http   www ssec wisc edu  tomw java unicode html  API        public static bool IsAlphaNumeric this string stringToTest                  English         const string charSet    a-zA-Z           const string numSet     0-9              Greek           const string charSet      u0388- u03EF                         const string numSet     0-9              Bengali           const string charSet      u0985- u09E3             const string numSet      u09E6- u09EF              Hindi           const string charSet      u0905- u0963             const string numSet      u0966- u096F            return Regex Match stringToTest             numSet             charSet                charSet             numSet             charSet   numSet          Success             public static bool IsNumeric this string stringToTest                  English         const string numSet     0-9              Hindi           const string numSet      u0966- u096F            return Regex Match stringToTest          numSet           Success             public static bool IsAlpha this string stringToTest                  English         const string charSet    a-zA-Z            return Regex Match stringToTest          charSet           Success          Usage              English         string test    AASD121asf              Greek           string test        123              Bengali           string test                      Hindi           string test                       bool isAlphaNum   test IsAlphaNumeric

User · Answer

There s a lot of verbosity in here  and I m deeply against it  so  my conclusive answer would be      w       w is equivalent to  A-Za-z0-9    which is pretty much what you want   unless we introduce unicode to the mix   Using the   quantifier you ll match one or more characters  If you want to accept an empty string too  use   instead

User · Answer

Um   question   Does it need to have at least one character or no   Can it be an empty string     A-Za-z0-9       Will do at least one upper or lower case alphanumeric or underscore   If it can be zero length  then just substitute the   for      A-Za-z0-9       Edit   If diacritics need to be included  such as cedilla -   231   then you would need to use the word character which does the same as the above  but includes the diacritic characters     w     Or    w

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To match a string that contains only those characters  or an empty string   try     a-zA-Z0-9        This works for  NET regular expressions  and probably a lot of other languages as well   Breaking it down       start of string     beginning of character group a-z   any lowercase letter A-Z   any uppercase letter 0-9   any digit     underscore     end of character group     zero or more of the given characters     end of string   If you don t want to allow empty strings  use   instead of       As others have pointed out  some regex languages have a shorthand form for  a-zA-Z0-9    In the  NET regex language  you can turn on ECMAScript behavior and use  w as a shorthand  yielding   w   or   w     Note that in other languages  and by default in  NET   w is somewhat broader  and will match other sorts of Unicode characters as well  thanks to Jan for pointing this out   So if you re really intending to match only those characters  using the explicit  longer  form is probably best

User · Answer

You want to check that each character matches your requirements  which is why we use    A-Za-z0-9     And you can even use the shorthand version    w   Which is equivalent  in some regex flavors  so make sure you check before you use it   Then to indicate that the entire string must match  you use       To indicate the string must start with that character  then use      To indicate the string must end with that character  Then use   w  or  w    To indicate  1 or more   or  0 or more   Putting it all together  we have     w

User · Answer

The following regex matches alphanumeric characters and underscore      a-zA-Z0-9       For example  in Perl      usr bin perl -w  my  arg1    ARGV 0      check that the string contains  only  one or more alphanumeric chars or underscores if   arg1       a-zA-Z0-9           print  Failed  n     else       print  Success  n

User · Answer

Here is the regex for what you want with a quantifier to specify at least 1 character and no more than 255 characters    a-zA-Z0-9    1 255

User · Answer

This works for me  found this in the O Reilly s  Mastering Regular Expressions       w      Explanation      asserts position at start of the string    w  matches any word character  equal to  a-zA-Z0-9        Quantifier     Matches between one and unlimited times  as many times as possible  giving back as needed  greedy     asserts position at the end of the string   Verify yourself    x000D   x000D  const regex      w     x000D  const str    nut cracker 12   x000D  let m  x000D   x000D  if   m   regex exec str       null    x000D         The result can be accessed through the  m -variable  x000D      m forEach  match  groupIndex    gt    x000D          console log  Found match  group   groupIndex     match     x000D          x000D    x000D   x000D   x000D

User · Answer

For those of you looking for unicode alphanumeric matching  you might want to do something like      p L   p Nd        Further reading at  http   unicode org reports tr18  and at http   www regular-expressions info unicode html

User · Answer

To match a string that contains only those characters  or an empty string   try     a-zA-Z0-9        This works for  NET regular expressions  and probably a lot of other languages as well   Breaking it down       start of string     beginning of character group a-z   any lowercase letter A-Z   any uppercase letter 0-9   any digit     underscore     end of character group     zero or more of the given characters     end of string   If you don t want to allow empty strings  use   instead of       As others have pointed out  some regex languages have a shorthand form for  a-zA-Z0-9    In the  NET regex language  you can turn on ECMAScript behavior and use  w as a shorthand  yielding   w   or   w     Note that in other languages  and by default in  NET   w is somewhat broader  and will match other sorts of Unicode characters as well  thanks to Jan for pointing this out   So if you re really intending to match only those characters  using the explicit  longer  form is probably best

User · Answer

To match a string that contains only those characters  or an empty string   try     a-zA-Z0-9        This works for  NET regular expressions  and probably a lot of other languages as well   Breaking it down       start of string     beginning of character group a-z   any lowercase letter A-Z   any uppercase letter 0-9   any digit     underscore     end of character group     zero or more of the given characters     end of string   If you don t want to allow empty strings  use   instead of       As others have pointed out  some regex languages have a shorthand form for  a-zA-Z0-9    In the  NET regex language  you can turn on ECMAScript behavior and use  w as a shorthand  yielding   w   or   w     Note that in other languages  and by default in  NET   w is somewhat broader  and will match other sorts of Unicode characters as well  thanks to Jan for pointing this out   So if you re really intending to match only those characters  using the explicit  longer  form is probably best

User · Answer

Here is the regex for what you want with a quantifier to specify at least 1 character and no more than 255 characters    a-zA-Z0-9    1 255

User · Answer

How about      A-Za-z   0-9            if you want to be explicit  or     w        if you prefer concise  Perl syntax

User · Answer

Although it s more verbose than  w  I personally appreciate the readability of the full POSIX character class names   http   www zytrax com tech web regex htm special    so I d say        alnum         However  while the documentation at the above links states that  w will  Match any character in the range 0 - 9  A - Z and a - z  equivalent of POSIX   alnum      I have not found this to be true  Not with grep -P anyway  You need to explicitly include the underscore if you use   alnum   but not if you use  w  You can t beat the following for short and sweet     w     Along with readability  using the POSIX character classes  http   www regular-expressions info posixbrackets html  means that your regex can work on non ASCII strings  which the range based regexes won t do since they rely on the underlying ordering of the ASCII characters which may be different from other character sets and will therefore exclude some non-ASCII characters  letters such as   339   which you might want to capture

User · Answer

I believe you are not taking Latin and Unicode characters in your matches  For example  if you need to take      or      chars  the use of   w  won t work   You can  alternatively  use this approach     A-Z  -  a-z  -  0-9       Hope it helps

User · Answer

How about      A-Za-z   0-9            if you want to be explicit  or     w        if you prefer concise  Perl syntax

User · Answer

To match a string that contains only those characters  or an empty string   try     a-zA-Z0-9        This works for  NET regular expressions  and probably a lot of other languages as well   Breaking it down       start of string     beginning of character group a-z   any lowercase letter A-Z   any uppercase letter 0-9   any digit     underscore     end of character group     zero or more of the given characters     end of string   If you don t want to allow empty strings  use   instead of       As others have pointed out  some regex languages have a shorthand form for  a-zA-Z0-9    In the  NET regex language  you can turn on ECMAScript behavior and use  w as a shorthand  yielding   w   or   w     Note that in other languages  and by default in  NET   w is somewhat broader  and will match other sorts of Unicode characters as well  thanks to Jan for pointing this out   So if you re really intending to match only those characters  using the explicit  longer  form is probably best

User · Answer

w   will work for below combinations  1 123 1av pRo av1

User · Answer

There s a lot of verbosity in here  and I m deeply against it  so  my conclusive answer would be      w       w is equivalent to  A-Za-z0-9    which is pretty much what you want   unless we introduce unicode to the mix   Using the   quantifier you ll match one or more characters  If you want to accept an empty string too  use   instead

User · Answer

For those of you looking for unicode alphanumeric matching  you might want to do something like      p L   p Nd        Further reading at  http   unicode org reports tr18  and at http   www regular-expressions info unicode html

User · Answer

To check the entire string and not allow empty strings  try    A-Za-z0-9

User · Answer

You want to check that each character matches your requirements  which is why we use    A-Za-z0-9     And you can even use the shorthand version    w   Which is equivalent  in some regex flavors  so make sure you check before you use it   Then to indicate that the entire string must match  you use       To indicate the string must start with that character  then use      To indicate the string must end with that character  Then use   w  or  w    To indicate  1 or more   or  0 or more   Putting it all together  we have     w

User · Answer

Um   question   Does it need to have at least one character or no   Can it be an empty string     A-Za-z0-9       Will do at least one upper or lower case alphanumeric or underscore   If it can be zero length  then just substitute the   for      A-Za-z0-9       Edit   If diacritics need to be included  such as cedilla -   231   then you would need to use the word character which does the same as the above  but includes the diacritic characters     w     Or    w

User · Answer

Although it s more verbose than  w  I personally appreciate the readability of the full POSIX character class names   http   www zytrax com tech web regex htm special    so I d say        alnum         However  while the documentation at the above links states that  w will  Match any character in the range 0 - 9  A - Z and a - z  equivalent of POSIX   alnum      I have not found this to be true  Not with grep -P anyway  You need to explicitly include the underscore if you use   alnum   but not if you use  w  You can t beat the following for short and sweet     w     Along with readability  using the POSIX character classes  http   www regular-expressions info posixbrackets html  means that your regex can work on non ASCII strings  which the range based regexes won t do since they rely on the underlying ordering of the ASCII characters which may be different from other character sets and will therefore exclude some non-ASCII characters  letters such as   339   which you might want to capture

User · Answer

Try these multi-lingual extensions I have made for string    IsAlphaNumeric - String must contain atleast 1 alpha  letter in Unicode range  specified in charSet  and atleast 1 number  specified in numSet   Also  the string should comprise only of alpha and numbers   IsAlpha - String should contain atleast 1 alpha  in the language charSet specified  and comprise only of alpha   IsNumeric - String should contain atleast 1 number  in the language numSet specified  and comprise only of numbers   The charSet numSet range for the desired language can be specified  The Unicode ranges are available on below link   http   www ssec wisc edu  tomw java unicode html  API        public static bool IsAlphaNumeric this string stringToTest                  English         const string charSet    a-zA-Z           const string numSet     0-9              Greek           const string charSet      u0388- u03EF                         const string numSet     0-9              Bengali           const string charSet      u0985- u09E3             const string numSet      u09E6- u09EF              Hindi           const string charSet      u0905- u0963             const string numSet      u0966- u096F            return Regex Match stringToTest             numSet             charSet                charSet             numSet             charSet   numSet          Success             public static bool IsNumeric this string stringToTest                  English         const string numSet     0-9              Hindi           const string numSet      u0966- u096F            return Regex Match stringToTest          numSet           Success             public static bool IsAlpha this string stringToTest                  English         const string charSet    a-zA-Z            return Regex Match stringToTest          charSet           Success          Usage              English         string test    AASD121asf              Greek           string test        123              Bengali           string test                      Hindi           string test                       bool isAlphaNum   test IsAlphaNumeric

User · Answer

There s a lot of verbosity in here  and I m deeply against it  so  my conclusive answer would be      w       w is equivalent to  A-Za-z0-9    which is pretty much what you want   unless we introduce unicode to the mix   Using the   quantifier you ll match one or more characters  If you want to accept an empty string too  use   instead

User · Answer

To check the entire string and not allow empty strings  try    A-Za-z0-9

User · Answer

For me there was an issue in that I want to distinguish between alpha  numeric and alpha numeric  so to ensure an alphanumeric string contains at least one alpha and at least one numeric  I used        a-zA-Z   1   d 1       d 1   a-zA-Z   1

User · Answer

There s a lot of verbosity in here  and I m deeply against it  so  my conclusive answer would be      w       w is equivalent to  A-Za-z0-9    which is pretty much what you want   unless we introduce unicode to the mix   Using the   quantifier you ll match one or more characters  If you want to accept an empty string too  use   instead

User · Answer

Um   question   Does it need to have at least one character or no   Can it be an empty string     A-Za-z0-9       Will do at least one upper or lower case alphanumeric or underscore   If it can be zero length  then just substitute the   for      A-Za-z0-9       Edit   If diacritics need to be included  such as cedilla -   231   then you would need to use the word character which does the same as the above  but includes the diacritic characters     w     Or    w

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use lookaheads to do the  at least one  stuff   Trust me it s much easier   Here s an example that would require 1-10 characters  containing at least one digit and one letter            d       A-Za-z   A-Za-z0-9  1 10     NOTE  could have used  w but then ECMA Unicode considerations come into play increasing the character coverage of the  w  word character

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use lookaheads to do the  at least one  stuff   Trust me it s much easier   Here s an example that would require 1-10 characters  containing at least one digit and one letter            d       A-Za-z   A-Za-z0-9  1 10     NOTE  could have used  w but then ECMA Unicode considerations come into play increasing the character coverage of the  w  word character

User · Answer

To check the entire string and not allow empty strings  try    A-Za-z0-9

User · Answer

this works for me you can try      p Alnum

User · Answer

w   will work for below combinations  1 123 1av pRo av1

User · Answer

Here is the regex for what you want with a quantifier to specify at least 1 character and no more than 255 characters    a-zA-Z0-9    1 255

User · Answer

How about      A-Za-z   0-9            if you want to be explicit  or     w        if you prefer concise  Perl syntax

User · Answer

Required Format Allow these 3   0142171547295 014-2171547295 123abc  Don t Allow other formats  validatePnrAndTicketNumber        let alphaNumericRegex    a-zA-Z0-9          let numericRegex    0-9          let numericdashRegex      1-9  3   -   0-9  10          this currBookingRefValue   this requestForm controls  quot bookingReference quot   value     if this currBookingRefValue length    14  amp  amp  this currBookingRefValue match numericdashRegex         this requestForm controls  quot bookingReference quot   setErrors   pattern   false        else if this currBookingRefValue length   6  amp  amp  this currBookingRefValue match alphaNumericRegex        this requestForm controls  quot bookingReference quot   setErrors   pattern   false        else if this currBookingRefValue length   13  amp  amp  this currBookingRefValue match numericRegex         this requestForm controls  quot bookingReference quot   setErrors   pattern   false        else      this requestForm controls  quot bookingReference quot   setErrors   pattern   true             lt input name  quot booking reference quot  type  quot text quot   class input-not-empty   quot bookingRef value quot      class  quot glyph-input form-control floating-label-input quot  id  quot bookings bookingReference quot      value  quot  quot  maxlength  quot 14 quot  aria-required  quot true quot  role  quot textbox quot   bookingRef     formControlName  quot bookingReference quot   focus   quot resetMessageField   quot   blur   quot validatePnrAndTicketNumber   quot   gt

User · Answer

This works for me  found this in the O Reilly s  Mastering Regular Expressions       w      Explanation      asserts position at start of the string    w  matches any word character  equal to  a-zA-Z0-9        Quantifier     Matches between one and unlimited times  as many times as possible  giving back as needed  greedy     asserts position at the end of the string   Verify yourself    x000D   x000D  const regex      w     x000D  const str    nut cracker 12   x000D  let m  x000D   x000D  if   m   regex exec str       null    x000D         The result can be accessed through the  m -variable  x000D      m forEach  match  groupIndex    gt    x000D          console log  Found match  group   groupIndex     match     x000D          x000D    x000D   x000D   x000D

User · Answer

The following regex matches alphanumeric characters and underscore      a-zA-Z0-9       For example  in Perl      usr bin perl -w  my  arg1    ARGV 0      check that the string contains  only  one or more alphanumeric chars or underscores if   arg1       a-zA-Z0-9           print  Failed  n     else       print  Success  n

User · Answer

You want to check that each character matches your requirements  which is why we use    A-Za-z0-9     And you can even use the shorthand version    w   Which is equivalent  in some regex flavors  so make sure you check before you use it   Then to indicate that the entire string must match  you use       To indicate the string must start with that character  then use      To indicate the string must end with that character  Then use   w  or  w    To indicate  1 or more   or  0 or more   Putting it all together  we have     w

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This should work in most of the cases        d   a-z   a-z d     gi  And by most I mean   abcd       True abcd12     True ab12cd     True 12abcd     True  1234       False     Explanation           - match the pattern starting and ending with   d   - match zero or more digits  a-z   - match an alphabet or underscore  a-z d    - match an alphabet or digit or underscore  gi - match globally across the string and case-insensitive

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This should work in most of the cases        d   a-z   a-z d     gi  And by most I mean   abcd       True abcd12     True ab12cd     True 12abcd     True  1234       False     Explanation           - match the pattern starting and ending with   d   - match zero or more digits  a-z   - match an alphabet or underscore  a-z d    - match an alphabet or digit or underscore  gi - match globally across the string and case-insensitive

User · Answer

The following regex matches alphanumeric characters and underscore      a-zA-Z0-9       For example  in Perl      usr bin perl -w  my  arg1    ARGV 0      check that the string contains  only  one or more alphanumeric chars or underscores if   arg1       a-zA-Z0-9           print  Failed  n     else       print  Success  n

User · Answer

You want to check that each character matches your requirements  which is why we use    A-Za-z0-9     And you can even use the shorthand version    w   Which is equivalent  in some regex flavors  so make sure you check before you use it   Then to indicate that the entire string must match  you use       To indicate the string must start with that character  then use      To indicate the string must end with that character  Then use   w  or  w    To indicate  1 or more   or  0 or more   Putting it all together  we have     w

User · Answer

this works for me you can try      p Alnum

[regex] Regular Expression for alphanumeric and underscores

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