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(python2.1-lib.info)curses.ascii

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Utilities for ASCII characters
==============================

Constants and set-membership functions for ASCII characters.  This
module was written by Eric S. Raymond <esr@thyrsus.com>.
This manual section was written by Eric S. Raymond <esr@thyrsus.com>.
_Added in Python version 1.6_

The `curses.ascii' module supplies name constants for ASCII characters
and functions to test membership in various ASCII character classes.
The constants supplied are names for control characters as follows:

Name                                 Meaning
------                               -----
NUL                                  
SOH                                  Start of heading, console interrupt
STX                                  Start of text
ETX                                  End of text
EOT                                  End of transmission
ENQ                                  Enquiry, goes with `ACK' flow
                                     control
ACK                                  Acknowledgement
BEL                                  Bell
BS                                   Backspace
TAB                                  Tab
HT                                   Alias for `TAB': "Horizontal tab"
LF                                   Line feed
NL                                   Alias for `LF': "New line"
VT                                   Vertical tab
FF                                   Form feed
CR                                   Carriage return
SO                                   Shift-out, begin alternate
                                     character set
SI                                   Shift-in, resume default character
                                     set
DLE                                  Data-link escape
DC1                                  XON, for flow control
DC2                                  Device control 2, block-mode flow
                                     control
DC3                                  XOFF, for flow control
DC4                                  Device control 4
NAK                                  Negative acknowledgement
SYN                                  Synchronous idle
ETB                                  End transmission block
CAN                                  Cancel
EM                                   End of medium
SUB                                  Substitute
ESC                                  Escape
FS                                   File separator
GS                                   Group separator
RS                                   Record separator, block-mode
                                     terminator
US                                   Unit separator
SP                                   Space
DEL                                  Delete

Note that many of these have little practical significance in modern
usage.  The mnemonics derive from teleprinter conventions that predate
digital computers.

The module supplies the following functions, patterned on those in the
standard C library:

`isalnum(c)'
     Checks for an ASCII alphanumeric character; it is equivalent to
     `isalpha(C) or isdigit(C)'.

`isalpha(c)'
     Checks for an ASCII alphabetic character; it is equivalent to
     `isupper(C) or islower(C)'.

`isascii(c)'
     Checks for a character value that fits in the 7-bit ASCII set.

`isblank(c)'
     Checks for an ASCII whitespace character.

`iscntrl(c)'
     Checks for an ASCII control character (in the range 0x00 to 0x1f).

`isdigit(c)'
     Checks for an ASCII decimal digit, `0' through `9'.  This is
     equivalent to `C in string.digits'.

`isgraph(c)'
     Checks for ASCII any printable character except space.

`islower(c)'
     Checks for an ASCII lower-case character.

`isprint(c)'
     Checks for any ASCII printable character including space.

`ispunct(c)'
     Checks for any printable ASCII character which is not a space or an
     alphanumeric character.

`isspace(c)'
     Checks for ASCII white-space characters; space, line feed,
     carriage return, form feed, horizontal tab, vertical tab.

`isupper(c)'
     Checks for an ASCII uppercase letter.

`isxdigit(c)'
     Checks for an ASCII hexadecimal digit.  This is equivalent to `C
     in string.hexdigits'.

`isctrl(c)'
     Checks for an ASCII control character (ordinal values 0 to 31).

`ismeta(c)'
     Checks for a non-ASCII character (ordinal values 0x80 and above).

These functions accept either integers or strings; when the argument is
a string, it is first converted using the built-in function `ord()'.

Note that all these functions check ordinal bit values derived from the
first character of the string you pass in; they do not actually know
anything about the host machine's character encoding.  For functions
that know about the character encoding (and handle internationalization
properly) see the `string' module.

The following two functions take either a single-character string or
integer byte value; they return a value of the same type.

`ascii(c)'
     Return the ASCII value corresponding to the low 7 bits of C.

`ctrl(c)'
     Return the control character corresponding to the given character
     (the character bit value is bitwise-anded with 0x1f).

`alt(c)'
     Return the 8-bit character corresponding to the given ASCII
     character (the character bit value is bitwise-ored with 0x80).

The following function takes either a single-character string or
integer value; it returns a string.

`unctrl(c)'
     Return a string representation of the ASCII character C.  If C is
     printable, this string is the character itself.  If the character
     is a control character (0x00-0x1f) the string consists of a caret
     (`^') followed by the corresponding uppercase letter.  If the
     character is an ASCII delete (0x7f) the string is `'^{}?''.  If
     the character has its meta bit (0x80) set, the meta bit is
     stripped, the preceding rules applied, and `!' prepended to the
     result.

`controlnames'
     A 33-element string array that contains the ASCII mnemonics for the
     thirty-two ASCII control characters from 0 (NUL) to 0x1f (US), in
     order, plus the mnemonic `SP' for the space character.