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(librep.info)Characters

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Characters
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   In `librep' characters are stored in integers. Their read syntax is
a question mark followed by the character itself, which may be an
escape sequence introduced by a backslash. For details of the available
escape sequences see Note: Strings.

     ?a
         => 97
     
     ?\n
         => 10
     
     ?\177
         => 127

 - Function: alpha-char-p character
     This function returns true when CHARACTER is one of the alphabetic
     characters.

          (alpha-char-p ?a)
              => t

 - Function: upper-case-p character
     When CHARACTER is one of the upper-case characters this function
     returns true.

 - Function: lower-case-p character
     Returns true when CHARACTER is lower-case.

 - Function: digit-char-p character
     This function returns true when CHARACTER is one of the decimal
     digit characters.

 - Function: alphanumericp character
     This function returns true when CHARACTER is either an alphabetic
     character or a decimal digit character.

 - Function: space-char-p character
     Returns true when CHARACTER is a white-space character (space, tab,
     newline or form feed).

 - Function: char-upcase character
     This function returns the upper-case equivalent of CHARACTER. If
     CHARACTER is already upper-case or has no upper-case equivalent it
     is returned unchanged.

          (char-upcase ?a)
              => 65                       ;`A'
          
          (char-upcase ?A)
              => 65                       ;`A'
          
          (char-upcase ?!)
              => 33                       ;`!'

 - Function: char-downcase character
     Returns the lower-case equivalent of the character CHARACTER.