Alphanumeric usernames and error message for it

Check for alphanumeric

For more details, look at the regex Q on SO.

$name="input string 123";
// Doesn"t allow:
// Pre-/Appending white space
// Not more than one space in between
// Non-alphanumeric characters (lower case)
if( ! preg_match( "/^[a-z0-9]+([\\s]{1}[a-z0-9]|[a-z0-9])+$/i", $name ) )
{
    // Output Error Message
}
// Or: Does only allow
// Alphanumeric character (lower & upper case)
// Dash & underline "-", "_" - makes (imho) sense
if( ! preg_match( "/^[A-Za-z0-9-_",'\s]+$/", $name ) )
{
    // Output Error Message
}

Error Message

You need to do this via Ajax. Best would be to look over the search results. Another (maybe) good reference would be to inspect the code of some ajax login plugins for a “how-to”.

Related Posts:

  1. Hebrew username
  2. How to translate “ERROR: Invalid username. Lost your password?”
  3. How to change a username?
  4. Change default ordering of display name
  5. use of nickname and nicename?
  6. How to retrieve lost username/ email log- in ?
  7. How can I allow Arabic usernames in WordPress
  8. Preg_Match(): compilation failed unknown property name
  9. Reset admin and password
  10. How to recover lost username?
  11. How to add @ symbol to user url
  12. How to assign a UserName value at creation
  13. How can hackers access WP usernames? [duplicate]
  14. Disable author admin just use name.
  15. I want to use my username to post blog posts, is this advisable?
  16. How is the AND/OR operator represented as in Regular Expressions?
  17. OR condition in Regex
  18. Using or ‘|’ in regex [duplicate]
  19. What is a Context Free Grammar?
  20. python .replace() regex [duplicate]
  21. Regex not operator
  22. What does \’.- mean in a Regular Expression
  23. Regex not operator
  24. What do ++ and *+ mean?
  25. How can I exclude one word with grep?
  26. Javascript split regex question
  27. How can I validate an email address using a regular expression?
  28. Regular expression to match a line that doesn’t contain a word
  29. Matching a space in regex
  30. Regex not operator
  31. How to accept space in regex?
  32. Difference between \b and \B in regex
  33. How to match “any character” in regular expression?
  34. regex match any whitespace
  35. Regex: ignore case sensitivity
  36. What does the regex \S mean in JavaScript?
  37. whitespace in regular expression
  38. How can I validate an email address using a regular expression?
  39. How do I use a regex in a shell script?
  40. Regex: ignore case sensitivity
  41. Python regex AttributeError: ‘NoneType’ object has no attribute ‘group’
  42. Regular Expression for alphanumeric and underscores
  43. What is the difference between the regular expressions [^\d\s] and [\D\S]
  44. Regex: AttributeError: ‘NoneType’ object has no attribute ‘groups’
  45. Regular Expression for alphanumeric and underscores
  46. re.sub erroring with “Expected string or bytes-like object”
  47. grep –ignore-case –only
  48. Regex AND operator
  49. python re.split() to split by spaces, commas, and periods, but not in cases like 1,000 or 1.50
  50. python re.split() to split by spaces, commas, and periods, but not in cases like 1,000 or 1.50
  51. Regex to test if string begins with http:// or https://
  52. Regular expression negative lookahead
  53. Regex how to match an optional character
  54. Regex lookahead, lookbehind and atomic groups
  55. Regular Expression to match string starting with a specific word
  56. Regular Expressions: Is there an AND operator?
  57. Writing a very simple lexical analyser in C++
  58. Regular expression to match standard 10 digit phone number
  59. Regular Expression.how to add optional character at end of regex
  60. Regular Expression with wildcards to match any character
  61. What is a non-capturing group in regular expressions?
  62. How to find all occurrences of a substring?
  63. What is a good regular expression to match a URL? [duplicate]
  64. What is a good regular expression to match a URL? [duplicate]
  65. Does “\d” in regex mean a digit?
  66. Understanding regex in Java: split(“\t”) vs split(“\\t”) – when do they both work, and when should they be used
  67. Is there a difference between /\s/g and /\s+/g?
  68. Split string on whitespace in Python
  69. How to validate an email address in PHP
  70. What is a non-capturing group in regular expressions?
  71. RegEx Ignore Case
  72. JavaScript replace/regex
  73. Regular expression to match standard 10 digit phone number
  74. How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
  75. Python string.replace regular expression
  76. Regex for numbers only
  77. How to match “any character” in regular expression?
  78. how to replace quotation marks with \”
  79. Remove all special characters, punctuation and spaces from string
  80. This can be done without regex:
  81. How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops
  82. Python string.replace regular expression
  83. Symbol for any number of any characters in regex?
  84. Grep and Python
  85. Regex – Does not contain certain Characters
  86. How to replace ” \ ” with ” \\ ” in java
  87. A regular expression to exclude a word/string
  88. Regex how to match an optional character
  89. How to validate an email address in JavaScript
  90. Remove properties from objects (JavaScript)
  91. Using Bash regex match (=~) where regex includes quotes (” characters)
  92. Searching for UUIDs in text with regex
  93. Regular expression to match a word or its prefix
  94. What does regular expression \\s*,\\s* do?
  95. How can I remove punctuation from input text in Java?
  96. Regular expression for exact match of a string
  97. Regex that accepts only numbers (0-9) and NO characters
  98. Using the star sign in grep
  99. Regex optional group
  100. Regex for string contains?
Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)