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Displaying keyword search results 11 - 15
Created by Dr. Xi on November 15, 2010 21:54:19    Last update: November 15, 2010 21:54:19
In the Perl for (foreach) loop, the looping variable is actually an alias (reference) to the original variable. Therefore, any changes applied to that variable are reflected in the original variable: C:\>perl @a = ('1', '2', '3'); for my $i (@a... This trick can be used to trim a Perl string: C:\>perl $s = ' abcd '; for ($s){ ...
Created by Fang on April 03, 2010 20:21:15    Last update: April 04, 2010 03:30:22
The tags <c:out> The <c:out> tag evaluates an expression and outputs the result on the page. The syntax is: <c:out value="value" [escapeXml="{true|false}"] ... where escapeXml defaults to true and default defaults to empty string "". <c:out value="${expr}" escapeXml="false"/> is equivalent to ${expr} . If a variable is set in multiple scopes, the lower scope wins. In the following example code, attribute1 is set in request, session, and application scopes; attribute2 is set in session and application scopes; attribute3 is set in the application scope. The results are: <c:out value="${attribute1}"/> : Attribute1 request scope <c:out value="${attribute2}"/> : Attribute2 session scope <c:out value="${attribute3}"/> : Attribute3 application scope To access values in higher scopes, you have to specify the scope explicitly, like this: <c:out value="${sessionScope.attribute1}"/> : Attribute1 session...
Created by Dr. Xi on December 05, 2009 20:12:16    Last update: December 05, 2009 20:46:45
It's quite easy for Perl to open a pipe and read from it: $file = "nospace.txt"; open(IN, "cat $file |") ... But the code breaks when the file name contains a space: # This does not work! $file = "yes space.txt"; ... On Windows, these don't work either: # This does not work! $file = "yes space.txt"; ... You need to use a technique called Safe Pipe Opens : $file = "yes space.txt"; $prog = "cat"; ...
Created by Dr. Xi on December 04, 2009 04:33:05    Last update: December 04, 2009 04:33:05
Variable Meaning $_ The default or implicit variable. @_ Within a subroutine the array @_ contains the parameters passed to that subroutine. $a, $b Special package variables when using sort() $<digit> Contains the subpattern from the corresponding set of capturing parentheses from the last pattern match, not counting patterns matched in nested blocks that have been exited already. $. Current line number for the last filehandle accessed. $/ The input record separator, newline by default. $| If set to nonzero, forces a flush right away and after every write or print on the currently selected output channel. Default is 0 (regardless of whether the channel is really buffered by the system or not; $| tells you only whether you've asked Perl explicitly to flush after...
Created by Dr. Xi on May 29, 2007 03:48:01    Last update: May 29, 2007 03:49:54
The following applies to Bourne, Korn and Bash: $var or ${var} Replaced by the value of var . Use braces to avoid ambiguity. ${var-value} Use the value of var if set, use value otherwise. ${var+value} Use the value of value if var is set, use nothing otherwise. ${var=value} Use the value of var if set, other wise, use value and assign value to var . ${var?value} Use the value of var ; otherwise, print value to standard error and exit the current shell. If value is omitted, a standard error message is printed instead.
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