(octave.info)Character Class Functions

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5.7 Character Class Functions
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Octave also provides the following character class test functions
patterned after the functions in the standard C library.  They all
operate on string arrays and return matrices of zeros and ones.
Elements that are nonzero indicate that the condition was true for the
corresponding character in the string array.  For example:

     isalpha ("!Q@WERT^Y&")
          ⇒ [ 0, 1, 0, 1, 1, 1, 1, 0, 1, 0 ]

 -- : isalnum (S)
     Return a logical array which is true where the elements of S are
     letters or digits and false where they are not.

     This is equivalent to (‘isalpha (S) | isdigit (S)’).

     See also: Note: isalpha, Note: isdigit,
     Note: ispunct, Note: isspace, Note:
     iscntrl.

 -- : isalpha (S)
     Return a logical array which is true where the elements of S are
     letters and false where they are not.

     This is equivalent to (‘islower (S) | isupper (S)’).

     See also: Note: isdigit, Note: ispunct,
     Note: isspace, Note: iscntrl, Note:
     isalnum, Note: islower, *note isupper:
     XREFisupper.

 -- : isletter (S)
     Return a logical array which is true where the elements of S are
     letters and false where they are not.

     This is an alias for the ‘isalpha’ function.

     See also: Note: isalpha, Note: isdigit,
     Note: ispunct, Note: isspace, Note:
     iscntrl, Note: isalnum.

 -- : islower (S)
     Return a logical array which is true where the elements of S are
     lowercase letters and false where they are not.

     See also: Note: isupper, Note: isalpha,
     Note: isletter, Note: isalnum.

 -- : isupper (S)
     Return a logical array which is true where the elements of S are
     uppercase letters and false where they are not.

     See also: Note: islower, Note: isalpha,
     Note: isletter, Note: isalnum.

 -- : isdigit (S)
     Return a logical array which is true where the elements of S are
     decimal digits (0-9) and false where they are not.

     See also: Note: isxdigit, Note: isalpha,
     Note: isletter, Note: ispunct, Note:
     isspace, Note: iscntrl.

 -- : isxdigit (S)
     Return a logical array which is true where the elements of S are
     hexadecimal digits (0-9 and a-fA-F).

     See also: Note: isdigit.

 -- : ispunct (S)
     Return a logical array which is true where the elements of S are
     punctuation characters and false where they are not.

     See also: Note: isalpha, Note: isdigit,
     Note: isspace, Note: iscntrl.

 -- : isspace (S)
     Return a logical array which is true where the elements of S are
     whitespace characters (space, formfeed, newline, carriage return,
     tab, and vertical tab) and false where they are not.

     See also: Note: iscntrl, Note: ispunct,
     Note: isalpha, Note: isdigit.

 -- : iscntrl (S)
     Return a logical array which is true where the elements of S are
     control characters and false where they are not.

     See also: Note: ispunct, Note: isspace,
     Note: isalpha, Note: isdigit.

 -- : isgraph (S)
     Return a logical array which is true where the elements of S are
     printable characters (but not the space character) and false where
     they are not.

     See also: Note: isprint.

 -- : isprint (S)
     Return a logical array which is true where the elements of S are
     printable characters (including the space character) and false
     where they are not.

     See also: Note: isgraph.

 -- : isascii (S)
     Return a logical array which is true where the elements of S are
     ASCII characters (in the range 0 to 127 decimal) and false where
     they are not.

 -- : isstrprop (STR, PROP)
     Test character string properties.

     For example:

          isstrprop ("abc123", "alpha")
          ⇒ [1, 1, 1, 0, 0, 0]

     If STR is a cell array, ‘isstrpop’ is applied recursively to each
     element of the cell array.

     Numeric arrays are converted to character strings.

     The second argument PROP must be one of

     "alpha"
          True for characters that are alphabetic (letters).

     "alnum"
     "alphanum"
          True for characters that are alphabetic or digits.

     "lower"
          True for lowercase letters.

     "upper"
          True for uppercase letters.

     "digit"
          True for decimal digits (0-9).

     "xdigit"
          True for hexadecimal digits (a-fA-F0-9).

     "space"
     "wspace"
          True for whitespace characters (space, formfeed, newline,
          carriage return, tab, vertical tab).

     "punct"
          True for punctuation characters (printing characters except
          space or letter or digit).

     "cntrl"
          True for control characters.

     "graph"
     "graphic"
          True for printing characters except space.

     "print"
          True for printing characters including space.

     "ascii"
          True for characters that are in the range of ASCII encoding.

     See also: Note: isalpha, Note: isalnum,
     Note: islower, Note: isupper, Note:
     isdigit, Note: isxdigit, *note isspace:
     XREFisspace, Note: ispunct, *note iscntrl:
     XREFiscntrl, Note: isgraph, *note isprint:
     XREFisprint, Note: isascii.