mirror of https://github.com/python/cpython.git
176 lines
5.8 KiB
TeX
176 lines
5.8 KiB
TeX
\section{\module{curses.ascii} ---
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Utilities for ASCII characters}
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\declaremodule{standard}{curses.ascii}
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\modulesynopsis{Constants and set-membership functions for
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\ASCII{} characters.}
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\moduleauthor{Eric S. Raymond}{esr@thyrsus.com}
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\sectionauthor{Eric S. Raymond}{esr@thyrsus.com}
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\versionadded{1.6}
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The \module{curses.ascii} module supplies name constants for
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\ASCII{} characters and functions to test membership in various
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\ASCII{} character classes. The constants supplied are names for
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control characters as follows:
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\begin{tableii}{l|l}{constant}{Name}{Meaning}
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\lineii{NUL}{}
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\lineii{SOH}{Start of heading, console interrupt}
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\lineii{STX}{Start of text}
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\lineii{ETX}{End of text}
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\lineii{EOT}{End of transmission}
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\lineii{ENQ}{Enquiry, goes with \constant{ACK} flow control}
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\lineii{ACK}{Acknowledgement}
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\lineii{BEL}{Bell}
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\lineii{BS}{Backspace}
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\lineii{TAB}{Tab}
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\lineii{HT}{Alias for \constant{TAB}: ``Horizontal tab''}
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\lineii{LF}{Line feed}
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\lineii{NL}{Alias for \constant{LF}: ``New line''}
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\lineii{VT}{Vertical tab}
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\lineii{FF}{Form feed}
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\lineii{CR}{Carriage return}
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\lineii{SO}{Shift-out, begin alternate character set}
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\lineii{SI}{Shift-in, resume default character set}
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\lineii{DLE}{Data-link escape}
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\lineii{DC1}{XON, for flow control}
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\lineii{DC2}{Device control 2, block-mode flow control}
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\lineii{DC3}{XOFF, for flow control}
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\lineii{DC4}{Device control 4}
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\lineii{NAK}{Negative acknowledgement}
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\lineii{SYN}{Synchronous idle}
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\lineii{ETB}{End transmission block}
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\lineii{CAN}{Cancel}
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\lineii{EM}{End of medium}
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\lineii{SUB}{Substitute}
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\lineii{ESC}{Escape}
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\lineii{FS}{File separator}
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\lineii{GS}{Group separator}
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\lineii{RS}{Record separator, block-mode terminator}
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\lineii{US}{Unit separator}
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\lineii{SP}{Space}
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\lineii{DEL}{Delete}
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\end{tableii}
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Note that many of these have little practical significance in modern
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usage. The mnemonics derive from teleprinter conventions that predate
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digital computers.
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The module supplies the following functions, patterned on those in the
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standard C library:
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\begin{funcdesc}{isalnum}{c}
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Checks for an \ASCII{} alphanumeric character; it is equivalent to
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\samp{isalpha(\var{c}) or isdigit(\var{c})}.
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\end{funcdesc}
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\begin{funcdesc}{isalpha}{c}
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Checks for an \ASCII{} alphabetic character; it is equivalent to
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\samp{isupper(\var{c}) or islower(\var{c})}.
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\end{funcdesc}
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\begin{funcdesc}{isascii}{c}
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Checks for a character value that fits in the 7-bit \ASCII{} set.
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\end{funcdesc}
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\begin{funcdesc}{isblank}{c}
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Checks for an \ASCII{} whitespace character.
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\end{funcdesc}
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\begin{funcdesc}{iscntrl}{c}
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Checks for an \ASCII{} control character (in the range 0x00 to 0x1f).
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\end{funcdesc}
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\begin{funcdesc}{isdigit}{c}
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Checks for an \ASCII{} decimal digit, \character{0} through
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\character{9}. This is equivalent to \samp{\var{c} in string.digits}.
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\end{funcdesc}
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\begin{funcdesc}{isgraph}{c}
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Checks for \ASCII{} any printable character except space.
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\end{funcdesc}
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\begin{funcdesc}{islower}{c}
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Checks for an \ASCII{} lower-case character.
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\end{funcdesc}
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\begin{funcdesc}{isprint}{c}
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Checks for any \ASCII{} printable character including space.
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\end{funcdesc}
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\begin{funcdesc}{ispunct}{c}
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Checks for any printable \ASCII{} character which is not a space or an
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alphanumeric character.
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\end{funcdesc}
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\begin{funcdesc}{isspace}{c}
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Checks for \ASCII{} white-space characters; space, line feed,
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carriage return, form feed, horizontal tab, vertical tab.
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\end{funcdesc}
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\begin{funcdesc}{isupper}{c}
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Checks for an \ASCII{} uppercase letter.
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\end{funcdesc}
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\begin{funcdesc}{isxdigit}{c}
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Checks for an \ASCII{} hexadecimal digit. This is equivalent to
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\samp{\var{c} in string.hexdigits}.
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\end{funcdesc}
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\begin{funcdesc}{isctrl}{c}
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Checks for an \ASCII{} control character (ordinal values 0 to 31).
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\end{funcdesc}
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\begin{funcdesc}{ismeta}{c}
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Checks for a non-\ASCII{} character (ordinal values 0x80 and above).
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\end{funcdesc}
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These functions accept either integers or strings; when the argument
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is a string, it is first converted using the built-in function
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\function{ord()}.
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Note that all these functions check ordinal bit values derived from the
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first character of the string you pass in; they do not actually know
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anything about the host machine's character encoding. For functions
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that know about the character encoding (and handle
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internationalization properly) see the \refmodule{string} module.
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The following two functions take either a single-character string or
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integer byte value; they return a value of the same type.
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\begin{funcdesc}{ascii}{c}
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Return the ASCII value corresponding to the low 7 bits of \var{c}.
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\end{funcdesc}
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\begin{funcdesc}{ctrl}{c}
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Return the control character corresponding to the given character
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(the character bit value is bitwise-anded with 0x1f).
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\end{funcdesc}
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\begin{funcdesc}{alt}{c}
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Return the 8-bit character corresponding to the given ASCII character
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(the character bit value is bitwise-ored with 0x80).
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\end{funcdesc}
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The following function takes either a single-character string or
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integer value; it returns a string.
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\begin{funcdesc}{unctrl}{c}
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Return a string representation of the \ASCII{} character \var{c}. If
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\var{c} is printable, this string is the character itself. If the
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character is a control character (0x00-0x1f) the string consists of a
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caret (\character{\^}) followed by the corresponding uppercase letter.
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If the character is an \ASCII{} delete (0x7f) the string is
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\code{'\^{}?'}. If the character has its meta bit (0x80) set, the meta
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bit is stripped, the preceding rules applied, and
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\character{!} prepended to the result.
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\end{funcdesc}
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\begin{datadesc}{controlnames}
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A 33-element string array that contains the \ASCII{} mnemonics for the
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thirty-two \ASCII{} control characters from 0 (NUL) to 0x1f (US), in
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order, plus the mnemonic \samp{SP} for the space character.
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\end{datadesc}
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