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Epsilon User's Manual and Reference
   Commands by Topic
      Changing Text
         . . .
         Replacing
         Regular Expressions
            Entering Special Characters
            Character Classes
            Regular Expression Examples
            . . .
         Rearranging
            Sorting
            Transposing
            Formatting Text
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Regular Expressions  Commands by Topic   Character Classes


Epsilon User's Manual and Reference > Commands by Topic > Changing Text > Regular Expressions >

Entering Special Characters

 <Comma>  ,  <Nul>  ^@  <Period>  .
 <Space>    <Star>  *  <Plus>  +
 <Enter>  ^M  <Percent>  %  <Vbar>  |
 <Return>  ^M  <Lparen>  (  <Question>  ?
 <Newline>  ^J  <Rparen>  )  <Query>  ?
 <Linefeed>  ^J  <Langle>  <  <Caret>  ^
 <Tab>  ^I  <Rangle>  >  <Dollar>  $
 <Bell>  ^G  <LSquare>  [  <Bang>  !
 <Backspace>  ^H  <RSquare>  ]  <Exclamation>  !
 <FormFeed>  ^L  <Lbracket>  [  <Quote>  '
 <Esc>  ^[  <Rbracket>  ]  <SQuote>  '
 <Escape>  ^[  <Dot>  .  <DQuote>  "
 <Null>  ^@  <Backslash>  \  <Tilde>  ~

In a regular expression, the percent ("%") character quotes the next character, removing any special meaning that character may have. For example, the expression x%+ refers to the string "x+", whereas the pattern x+ refers to the set that contains "x", "xx", "xxx", and so on.

You can also quote characters by enclosing them in angle brackets. The expression x<+> refers to the string "x+", the same as x%+. In place of the character itself, you can provide the name of the character inside the angle brackets. The table lists some of the character names Epsilon recognizes; you can also use any character name in the Unicode standard, such as <Superscript two>.

To search for the NUL character (the character with ASCII code 0), use the expression <Nul>, because an actual NUL character may not appear in a regular expression.

Instead of the character's name, you can provide its numeric value using the notation <#number>. The sequence <#number> denotes the character with ASCII code number. For example, the pattern <#0> provides another way to specify the NUL character, and the pattern abc<#10>+ specifies the set of strings that begin with "abc" and end with one or more newline characters (newline has ASCII value 10). You can enter the value in hexadecimal, octal, or binary by prefixing the number with "0x", "0o", or "0b", respectively. For example, <#32>, <#0x20>, <#0o40>, and <#0b100000> all yield a <Space> character (ASCII code 32).



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