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I need a regex which will allow only A-Z, a-z, 0-9, the _ character, and dot (.) in the input.
I tried:
[A-Za-z0-9_.] But, it did not work. How can I fix it?
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Most characters, including all letters ( a-z and A-Z ) and digits ( 0-9 ), match itself. For example, the regex x matches substring "x" ; z matches "z" ; and 9 matches "9" . Non-alphanumeric characters without special meaning in regex also matches itself. For example, = matches "=" ; @ matches "@" .
To match any number from 0 to 9 we use \d in regex. It will match any single digit number from 0 to 9. \d means [0-9] or match any number from 0 to 9. Instead of writing 0123456789 the shorthand version is [0-9] where [] is used for character range.
The regex [0-9] matches single-digit numbers 0 to 9. [1-9][0-9] matches double-digit numbers 10 to 99. Something like ^[2-9][1-6]$ matches 21 or even 96! Any help would be appreciated.
The regular expression [A-Z][a-z]* matches any sequence of letters that starts with an uppercase letter and is followed by zero or more lowercase letters.
^[A-Za-z0-9_.]+$ From beginning until the end of the string, match one or more of these characters.
Edit:
Note that ^ and $ match the beginning and the end of a line. When multiline is enabled, this can mean that one line matches, but not the complete string.
Use \A for the beginning of the string, and \z for the end.
See for example: http://msdn.microsoft.com/en-us/library/h5181w5w(v=vs.110).aspx
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