[Python-checkins] CVS: python/dist/src/Doc/lib libre.tex,1.71,1.72

[Fred L. Drake]

Update of /cvsroot/python/python/dist/src/Doc/lib
In directory usw-pr-cvs1:/tmp/cvs-serv18154/lib

Modified Files:
	libre.tex 
Log Message:
New section of regular expression examples contributed by Skip Montanaro,
with some extensions and changes from me.
This closes SF patch #472825.


Index: libre.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libre.tex,v
retrieving revision 1.71
retrieving revision 1.72
diff -C2 -d -r1.71 -r1.72
*** libre.tex	2001/11/05 21:34:36	1.71
--- libre.tex	2001/11/29 08:45:22	1.72
***************
*** 793,794 ****
--- 793,850 ----
  The string passed to \function{match()} or \function{search()}.
  \end{memberdesc}
+ 
+ \subsection{Examples}
+ 
+ %\begin{list}{}{\leftmargin 0.7in \labelwidth 0.65in}
+ 
+ %\item[Simulating scanf]
+ 
+ \leftline{\strong{Simulating \cfunction{scanf()}}}
+ 
+ Python does not currently have an equivalent to \cfunction{scanf()}.
+ \ttindex{scanf()}
+ Regular expressions are generally more powerful, though also more
+ verbose, than \cfunction{scanf()} format strings.  The table below
+ offers some more-or-less equivalent mappings between
+ \cfunction{scanf()} format tokens and regular expressions.
+ 
+ \begin{tableii}{l|l}{textrm}{\cfunction{scanf()} Token}{Regular Expression}
+   \lineii{\code{\%c}}
+          {\regexp{.}}
+   \lineii{\code{\%5c}}
+          {\regexp{.\{5\}}}
+   \lineii{\code{\%d}}
+          {\regexp{[-+]\e d+}}
+   \lineii{\code{\%e}, \code{\%E}, \code{\%f}, \code{\%g}}
+          {\regexp{[-+](\e d+(\e.\e d*)?|\e d*\e.\e d+)([eE]\e d+)?}}
+   \lineii{\code{\%i}}
+          {\regexp{[-+](0[xX][\e dA-Fa-f]+|0[0-7]*|\e d+)}}
+   \lineii{\code{\%o}}
+          {\regexp{0[0-7]*}}
+   \lineii{\code{\%s}}
+          {\regexp{[\textasciicircum\e s]+}}
+   \lineii{\code{\%u}}
+          {\regexp{\e d+}}
+   \lineii{\code{\%x}, \code{\%X}}
+          {\regexp{0[xX][\e dA-Fa-f]}}
+ \end{tableii}
+ 
+ To extract the filename and numbers from a string like
+ 
+ \begin{verbatim}
+     /usr/sbin/sendmail - 0 errors, 4 warnings
+ \end{verbatim}
+ 
+ you would use a \cfunction{scanf()} format like
+ 
+ \begin{verbatim}
+     %s - %d errors, %d warnings
+ \end{verbatim}
+ 
+ The equivalent regular expression would be
+ 
+ \begin{verbatim}
+     ([^\s]+) - (\d+) errors, (\d+) warnings
+ \end{verbatim}
+ 
+ %\end{list}