198 lines
6.9 KiB
TeX
198 lines
6.9 KiB
TeX
\section{Standard Module \sectcode{string}}
|
|
|
|
\stmodindex{string}
|
|
|
|
This module defines some constants useful for checking character
|
|
classes and some useful string functions. See the modules
|
|
\code{regex} and \code{regsub} for string functions based on regular
|
|
expressions.
|
|
|
|
The constants defined in this module are are:
|
|
|
|
\renewcommand{\indexsubitem}{(data in module string)}
|
|
\begin{datadesc}{digits}
|
|
The string \code{'0123456789'}.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{hexdigits}
|
|
The string \code{'0123456789abcdefABCDEF'}.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{letters}
|
|
The concatenation of the strings \code{lowercase} and
|
|
\code{uppercase} described below.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{lowercase}
|
|
A string containing all the characters that are considered lowercase
|
|
letters. On most systems this is the string
|
|
\code{'abcdefghijklmnopqrstuvwxyz'}. Do not change its definition ---
|
|
the effect on the routines \code{upper} and \code{swapcase} is
|
|
undefined.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{octdigits}
|
|
The string \code{'01234567'}.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{uppercase}
|
|
A string containing all the characters that are considered uppercase
|
|
letters. On most systems this is the string
|
|
\code{'ABCDEFGHIJKLMNOPQRSTUVWXYZ'}. Do not change its definition ---
|
|
the effect on the routines \code{lower} and \code{swapcase} is
|
|
undefined.
|
|
\end{datadesc}
|
|
|
|
\begin{datadesc}{whitespace}
|
|
A string containing all characters that are considered whitespace.
|
|
On most systems this includes the characters space, tab, linefeed,
|
|
return, formfeed, and vertical tab. Do not change its definition ---
|
|
the effect on the routines \code{strip} and \code{split} is
|
|
undefined.
|
|
\end{datadesc}
|
|
|
|
The functions defined in this module are:
|
|
|
|
\renewcommand{\indexsubitem}{(in module string)}
|
|
|
|
\begin{funcdesc}{atof}{s}
|
|
Convert a string to a floating point number. The string must have
|
|
the standard syntax for a floating point literal in Python, optionally
|
|
preceded by a sign (\samp{+} or \samp{-}).
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{atoi}{s\optional{\, base}}
|
|
Convert string \var{s} to an integer in the given \var{base}. The
|
|
string must consist of one or more digits, optionally preceded by a
|
|
sign (\samp{+} or \samp{-}). The \var{base} defaults to 10. If it is
|
|
0, a default base is chosen depending on the leading characters of the
|
|
string (after stripping the sign): \samp{0x} or \samp{0X} means 16,
|
|
\samp{0} means 8, anything else means 10. If \var{base} is 16, a
|
|
leading \samp{0x} or \samp{0X} is always accepted. (Note: for a more
|
|
flexible interpretation of numeric literals, use the built-in function
|
|
\code{eval()}.)
|
|
\bifuncindex{eval}
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{atol}{s\optional{\, base}}
|
|
Convert string \var{s} to a long integer in the given \var{base}. The
|
|
string must consist of one or more digits, optionally preceded by a
|
|
sign (\samp{+} or \samp{-}). The \var{base} argument has the same
|
|
meaning as for \code{atoi()}. A trailing \samp{l} or \samp{L} is not
|
|
allowed.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{expandtabs}{s\, tabsize}
|
|
Expand tabs in a string, i.e.\ replace them by one or more spaces,
|
|
depending on the current column and the given tab size. The column
|
|
number is reset to zero after each newline occurring in the string.
|
|
This doesn't understand other non-printing characters or escape
|
|
sequences.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{find}{s\, sub\optional{\, start}}
|
|
Return the lowest index in \var{s} not smaller than \var{start} where the
|
|
substring \var{sub} is found. Return \code{-1} when \var{sub}
|
|
does not occur as a substring of \var{s} with index at least \var{start}.
|
|
If \var{start} is omitted, it defaults to \code{0}. If \var{start} is
|
|
negative, \code{len(\var{s})} is added.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{rfind}{s\, sub\optional{\, start}}
|
|
Like \code{find} but find the highest index.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{index}{s\, sub\optional{\, start}}
|
|
Like \code{find} but raise \code{ValueError} when the substring is
|
|
not found.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{rindex}{s\, sub\optional{\, start}}
|
|
Like \code{rfind} but raise \code{ValueError} when the substring is
|
|
not found.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{count}{s\, sub\optional{\, start}}
|
|
Return the number of (non-overlapping) occurrences of substring
|
|
\var{sub} in string \var{s} with index at least \var{start}.
|
|
If \var{start} is omitted, it defaults to \code{0}. If \var{start} is
|
|
negative, \code{len(\var{s})} is added.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{lower}{s}
|
|
Convert letters to lower case.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{split}{s}
|
|
Return a list of the whitespace-delimited words of the string
|
|
\var{s}.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{splitfields}{s\, sep}
|
|
Return a list containing the fields of the string \var{s}, using
|
|
the string \var{sep} as a separator. The list will have one more
|
|
items than the number of non-overlapping occurrences of the
|
|
separator in the string. Thus, \code{string.splitfields(\var{s}, '
|
|
')} is not the same as \code{string.split(\var{s})}, as the latter
|
|
only returns non-empty words. As a special case,
|
|
\code{splitfields(\var{s}, '')} returns \code{[\var{s}]}, for any string
|
|
\var{s}. (See also \code{regsub.split()}.)
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{join}{words}
|
|
Concatenate a list or tuple of words with intervening spaces.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{joinfields}{words\, sep}
|
|
Concatenate a list or tuple of words with intervening separators.
|
|
It is always true that
|
|
\code{string.joinfields(string.splitfields(\var{t}, \var{sep}), \var{sep})}
|
|
equals \var{t}.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{strip}{s}
|
|
Remove leading and trailing whitespace from the string
|
|
\var{s}.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{swapcase}{s}
|
|
Convert lower case letters to upper case and vice versa.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{translate}{s, table}
|
|
Translate the characters from \var{s} using \var{table}, which must be
|
|
a 256-character string giving the translation for each character
|
|
value, indexed by its ordinal.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{upper}{s}
|
|
Convert letters to upper case.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{ljust}{s\, width}
|
|
\funcline{rjust}{s\, width}
|
|
\funcline{center}{s\, width}
|
|
These functions respectively left-justify, right-justify and center a
|
|
string in a field of given width.
|
|
They return a string that is at least
|
|
\var{width}
|
|
characters wide, created by padding the string
|
|
\var{s}
|
|
with spaces until the given width on the right, left or both sides.
|
|
The string is never truncated.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{zfill}{s\, width}
|
|
Pad a numeric string on the left with zero digits until the given
|
|
width is reached. Strings starting with a sign are handled correctly.
|
|
\end{funcdesc}
|
|
|
|
This module is implemented in Python. Much of its functionality has
|
|
been reimplemented in the built-in module \code{strop}. However, you
|
|
should \emph{never} import the latter module directly. When
|
|
\code{string} discovers that \code{strop} exists, it transparently
|
|
replaces parts of itself with the implementation from \code{strop}.
|
|
After initialization, there is \emph{no} overhead in using
|
|
\code{string} instead of \code{strop}.
|
|
\bimodindex{strop}
|