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Diffstat (limited to 'Doc/tut')
| -rw-r--r-- | Doc/tut/tut.tex | 75 |
1 files changed, 45 insertions, 30 deletions
diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex index 50ba5e9..a3bb6ba 100644 --- a/Doc/tut/tut.tex +++ b/Doc/tut/tut.tex @@ -657,15 +657,14 @@ the first line above could also have been written \samp{word = 'Help' expressions: \begin{verbatim} ->>> import string >>> 'str' 'ing' # <- This is ok 'string' ->>> string.strip('str') + 'ing' # <- This is ok +>>> 'str'.strip() + 'ing' # <- This is ok 'string' ->>> string.strip('str') 'ing' # <- This is invalid +>>> 'str'.strip() 'ing' # <- This is invalid File "<stdin>", line 1, in ? - string.strip('str') 'ing' - ^ + 'str'.strip() 'ing' + ^ SyntaxError: invalid syntax \end{verbatim} @@ -807,6 +806,21 @@ The built-in function \function{len()} returns the length of a string: \end{verbatim} +\begin{seealso} + \seetitle[../lib/typesseq.html]{Sequence Types}% + {Strings, and the Unicode strings described in the next + section, are examples of \emph{sequence types}, and + support the common operations supported by such types.} + \seetitle[../lib/string-methods.html]{String Methods}% + {Both strings and Unicode strings support a large number of + methods for basic transformations and searching.} + \seetitle[../lib/typesseq-strings.html]{String Formatting Operations}% + {The formatting operations invoked when strings and Unicode + strings are the left operand of the \code{\%} operator are + described in more detail here.} +\end{seealso} + + \subsection{Unicode Strings \label{unicodeStrings}} \sectionauthor{Marc-Andre Lemburg}{mal@lemburg.com} @@ -1516,7 +1530,7 @@ TypeError: function() got multiple values for keyword argument 'a' \end{verbatim} When a final formal parameter of the form \code{**\var{name}} is -present, it receives a dictionary containing all keyword arguments +present, it receives a \ulink{dictionary}{../lib/typesmapping.html} containing all keyword arguments whose keyword doesn't correspond to a formal parameter. This may be combined with a formal parameter of the form \code{*\var{name}} (described in the next subsection) which receives a @@ -1978,9 +1992,10 @@ another value is assigned to it). We'll find other uses for We saw that lists and strings have many common properties, such as indexing and slicing operations. They are two examples of -\emph{sequence} data types. Since Python is an evolving language, -other sequence data types may be added. There is also another -standard sequence data type: the \emph{tuple}. +\ulink{\emph{sequence} data types}{../lib/typesseq.html}. Since +Python is an evolving language, other sequence data types may be +added. There is also another standard sequence data type: the +\emph{tuple}. A tuple consists of a number of values separated by commas, for instance: @@ -2050,7 +2065,8 @@ always creates a tuple, and unpacking works for any sequence. \section{Dictionaries \label{dictionaries}} -Another useful data type built into Python is the \emph{dictionary}. +Another useful data type built into Python is the +\ulink{\emph{dictionary}}{../lib/typesmapping.html}. Dictionaries are sometimes found in other languages as ``associative memories'' or ``associative arrays''. Unlike sequences, which are indexed by a range of numbers, dictionaries are indexed by \emph{keys}, @@ -2078,11 +2094,11 @@ If you store using a key that is already in use, the old value associated with that key is forgotten. It is an error to extract a value using a non-existent key. -The \code{keys()} method of a dictionary object returns a list of all +The \method{keys()} method of a dictionary object returns a list of all the keys used in the dictionary, in random order (if you want it -sorted, just apply the \code{sort()} method to the list of keys). To +sorted, just apply the \method{sort()} method to the list of keys). To check whether a single key is in the dictionary, use the -\code{has_key()} method of the dictionary. +\method{has_key()} method of the dictionary. Here is a small example using a dictionary: @@ -2872,11 +2888,10 @@ The value of x is 32.5, and y is 40000... Here are two ways to write a table of squares and cubes: \begin{verbatim} ->>> import string >>> for x in range(1, 11): -... print string.rjust(repr(x), 2), string.rjust(repr(x*x), 3), +... print repr(x).rjust(2), repr(x*x).rjust(3), ... # Note trailing comma on previous line -... print string.rjust(repr(x*x*x), 4) +... print repr(x*x*x).rjust(4) ... 1 1 1 2 4 8 @@ -2906,28 +2921,27 @@ Here are two ways to write a table of squares and cubes: (Note that one space between each column was added by the way \keyword{print} works: it always adds spaces between its arguments.) -This example demonstrates the function \function{string.rjust()}, +This example demonstrates the \method{rjust()} method of string objects, which right-justifies a string in a field of a given width by padding -it with spaces on the left. There are similar functions -\function{string.ljust()} and \function{string.center()}. These -functions do not write anything, they just return a new string. If +it with spaces on the left. There are similar methods +\method{ljust()} and \method{center()}. These +methods do not write anything, they just return a new string. If the input string is too long, they don't truncate it, but return it unchanged; this will mess up your column lay-out but that's usually better than the alternative, which would be lying about a value. (If you really want truncation you can always add a slice operation, as in -\samp{string.ljust(x,~n)[0:n]}.) +\samp{x.ljust(~n)[:n]}.) -There is another function, \function{string.zfill()}, which pads a +There is another method, \method{zfill()}, which pads a numeric string on the left with zeros. It understands about plus and minus signs: \begin{verbatim} ->>> import string ->>> string.zfill('12', 5) +>>> '12'.zfill(5) '00012' ->>> string.zfill('-3.14', 7) +>>> '-3.14'.zfill(7) '-003.14' ->>> string.zfill('3.14159265359', 5) +>>> '3.14159265359'.zfill(5) '3.14159265359' \end{verbatim} @@ -3110,7 +3124,7 @@ objects. Strings can easily be written to and read from a file. Numbers take a bit more effort, since the \method{read()} method only returns strings, which will have to be passed to a function like -\function{string.atoi()}, which takes a string like \code{'123'} and +\function{int()}, which takes a string like \code{'123'} and returns its numeric value 123. However, when you want to save more complex data types like lists, dictionaries, or class instances, things get a lot more complicated. @@ -3297,12 +3311,12 @@ error message and then re-raise the exception (allowing a caller to handle the exception as well): \begin{verbatim} -import string, sys +import sys try: f = open('myfile.txt') s = f.readline() - i = int(string.strip(s)) + i = int(s.strip()) except IOError, (errno, strerror): print "I/O error(%s): %s" % (errno, strerror) except ValueError: @@ -4466,7 +4480,8 @@ Tab: complete \end{verbatim} in your \file{\~{}/.inputrc}. (Of course, this makes it harder to -type indented continuation lines.) +type indented continuation lines if you're accustomed to using +\kbd{Tab} for that purpose.) Automatic completion of variable and module names is optionally available. To enable it in the interpreter's interactive mode, add |