why do inode indices starts from 1 unlike array indexes which starts from 0
its a question from "the design of unix operating system" of maurice j bach
id be glad if i get to know the answer quickly
:) (0 Replies)
brothers why inode index starts from 1 unlike array inex which starts from 0
its a question from the design of unix operating system of maurice j.bach
i need to know the answer urgently...someone help please (1 Reply)
I come across the problems when assigning the array in the script below . How to use the array with the 'string index' correctly ? When I assign a new string index , the array elements that are previously assigned are all changed .:eek::eek::eek:
$ array=211
$ echo ${array}
211
$... (4 Replies)
hi folks
i am facing problom while trying to access sql variable as array index ina unix shell script....script goes as below..
#!/bin/ksh
MAX=3
for elem in alpha beeta gaama
do
arr=$elem
((x=x+1))
Done
SQL_SERVER='servername'
/apps/sun5/utils/sqsh -S $SQL_SERVER -U user -P pwd -b -h... (1 Reply)
Hi,
I'm just trying to use a dynamic index for some array elements that I'm accessing within a loop. Specifically, I want to access an array at variable position $counter and then also at location $counter + 1 and $counter + 2 (the second and third array positions after it) but I keep getting... (0 Replies)
I am trying to reformat the table by filling any missing rows. The final table will have consecutive IDs in the first column. My problem is the index of the associate array in the awk script.
infile:
S01 36407 53706 88540
S02 69343 87098 87316
S03 50133 59721 107923... (4 Replies)
I am trying to assign indexes to an associative array in a for loop but I have to use an eval command to make it work, this doesn't seem correct I don't have to do this with regular arrays
For example, the following assignment fails without the eval command:
#! /bin/bash
read -d "\0" -a... (19 Replies)
Hello,
I have a complicated situational find and replace that I wrote in bash because I didn't know how to do everything in awk. The code works but is very slow, as expected.
To create my modified file, I am looping through an array that was populated earlier and making some replacements at... (6 Replies)
Perl::Critic::Policy::ErrorHandling::RequireCheckingRetuUserlContributedPerl::Critic::Policy::ErrorHandling::RequireCheckingReturnValueOfEval(3pm)NAME
Perl::Critic::Policy::ErrorHandling::RequireCheckingReturnValueOfEval - You can't depend upon the value of "$@"/"$EVAL_ERROR" to tell
whether an "eval" failed.
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
A common idiom in perl for dealing with possible errors is to use "eval" followed by a check of $@/$EVAL_ERROR:
eval {
...
};
if ($EVAL_ERROR) {
...
}
There's a problem with this: the value of $EVAL_ERROR can change between the end of the "eval" and the "if" statement. The issue is object
destructors:
package Foo;
...
sub DESTROY {
...
eval { ... };
...
}
package main;
eval {
my $foo = Foo->new();
...
};
if ($EVAL_ERROR) {
...
}
Assuming there are no other references to $foo created, when the "eval" block in "main" is exited, "Foo::DESTROY()" will be invoked,
regardless of whether the "eval" finished normally or not. If the "eval" in "main" fails, but the "eval" in "Foo::DESTROY()" succeeds,
then $EVAL_ERROR will be empty by the time that the "if" is executed. Additional issues arise if you depend upon the exact contents of
$EVAL_ERROR and both "eval"s fail, because the messages from both will be concatenated.
Even if there isn't an "eval" directly in the "DESTROY()" method code, it may invoke code that does use "eval" or otherwise affects
$EVAL_ERROR.
The solution is to ensure that, upon normal exit, an "eval" returns a true value and to test that value:
# Constructors are no problem.
my $object = eval { Class->new() };
# To cover the possiblity that an operation may correctly return a
# false value, end the block with "1":
if ( eval { something(); 1 } ) {
...
}
eval {
...
1;
}
or do {
# Error handling here
};
Unfortunately, you can't use the "defined" function to test the result; "eval" returns an empty string on failure.
Various modules have been written to take some of the pain out of properly localizing and checking $@/$EVAL_ERROR. For example:
use Try::Tiny;
try {
...
} catch {
# Error handling here;
# The exception is in $_/$ARG, not $@/$EVAL_ERROR.
}; # Note semicolon.
"But we don't use DESTROY() anywhere in our code!" you say. That may be the case, but do any of the third-party modules you use have them?
What about any you may use in the future or updated versions of the ones you already use?
CONFIGURATION
This Policy is not configurable except for the standard options.
SEE ALSO
See thread on perl5-porters starting here: http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-06/msg00537.html
<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-06/msg00537.html>.
For a nice, easy, non-magical way of properly handling exceptions, see Try::Tiny.
AUTHOR
Elliot Shank "<perl@galumph.com>"
COPYRIGHT
Copyright (c) 2008-2011 Elliot Shank.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license
can be found in the LICENSE file included with this module.
perl v5.14.22012Perl::Critic::Policy::ErrorHandling::RequireCheckingReturnValueOfEval(3pm)