Author Archive
How to Enable CURL in WAMP?
CURL is not enabled by default in WAMP. Every php programmer have to use CURL to make remote connection.
The steps are as follows :
1) Close WAMP (if running)
2) Navigate to WAMP\bin\php\(your version of php)\
3) edit php.ini
4) Search for curl, uncomment extension=php_curl.dll
5) Navigate to WAMP\bin\Apache\(your version of apache)\bin\
6) edit php.ini
7) Search for curl, uncomment extension=php_curl.dll
8 ) Save both
9) Restart WAMP
That will solve your Curl issues.
Enjoy!
Perl Interview Questions?
What is use of ‘strict’ in perl ?
The module strict restricts ‘unsafe constructs’, according to the perldocs
When you enable the strict module, the three things that Perl becomes strict about are:
• Variables ‘vars’
• References ‘refs’
• Subroutines ‘subs’
Strict variables are useful. Essentially, this means that all variables must be declared, that is defined before use. Furthermore, each variable must be defined with my or fully qualified
What is scalars in perl ?
The most basic kind of variable in Perl is the scalar variable. Scalar variables hold both strings and numbers, and are remarkable in that strings and numbers are completely interchangable. For example, the statement
$priority = 9;
sets the scalar variable $priority to 9, but you can also assign a string to exactly the same variable:
$priority = ‘high’
Perl difference between lists and arrays ?
A list is a fixed collection of scalars. An array is a variable that holds a variable collection of scalars.
Array operations, which change the scalars, reaaranges them, or adds or subtracts some scalars, only work on arrays. These can’t work on a list, which is fixed. Array operations include shift, unshift, push, pop, and splice.
You can change an array element, but you can’t change a list element.
What is the use of ‘defined’?
defined EXPR
defined
Returns true if EXPR has a value other than the undef value, or checks the value of $_ if EXPR is not specified.
If EXPR is a function or function reference, then it returns true if the function has been defined.
Return Value
• 0 if EXPR contains undef
• 1 if EXPR contains a valid value or reference
#!/usr/bin/perl $var1 = "This is defined"; if( defined($var1) ){ print "$var1\n"; } if( defined($var2) ){ print "var2 is also defined\n"; }else{ print "var2 is not defined\n"; } This will produce following result This is defined var2 is not defined |
Perl 5 cheat sheet
This ‘cheat sheet’ is a handy reference, meant for beginning Perl programmers. Not everything is mentioned, but 195 features may already be overwhelming.
Perl 5 cheat sheet v8
CONTEXTS SIGILS ARRAYS HASHES
void $scalar whole: @array %hash
scalar @array slice: @array[0, 2] @hash{'a', 'b'}
list %hash element: $array[0] $hash{'a'}
&sub
*glob SCALAR VALUES
number, string, reference, glob, undef
REFERENCES
\ references $$foo[1] aka $foo->[1]
$@%&* dereference $$foo{bar} aka $foo->{bar}
[] anon. arrayref ${$$foo[1]}[2] aka $foo->[1]->[2]
{} anon. hashref ${$$foo[1]}[2] aka $foo->[1][2]
\() list of refs
NUMBERS vs STRINGS LINKS
OPERATOR PRECEDENCE = = perl.plover.com
-> + . search.cpan.org
++ -- == != eq ne cpan.org
** < > <= >= lt gt le ge pm.org
! ~ \ u+ u- <=> cmp tpj.com
=~ !~ perldoc.com
* / % x SYNTAX
+ - . for (LIST) { }, for (a;b;c) { }
<< >> while ( ) { }, until ( ) { }
named uops if ( ) { } elsif ( ) { } else { }
< > <= >= lt gt le ge unless ( ) { } elsif ( ) { } else { }
== != <=> eq ne cmp for equals foreach (ALWAYS)
&
| ^ REGEX METACHARS REGEX MODIFIERS
&& ^ string begin /i case insens.
|| $ str. end (before \n) /m line based ^$
.. ... + one or more /s . includes \n
?: * zero or more /x ign. wh.space
= += -= *= etc. ? zero or one /g global
, => {3,7} repeat in range
list ops () capture REGEX CHARCLASSES
not (?:) no capture . == [^\n]
and [] character class \s == [\x20\f\t\r\n]
or xor | alternation \w == [A-Za-z0-9_]
\b word boundary \d == [0-9]
\z string end \S, \W and \D negate
DO
use strict; DON'T LINKS
use warnings; "$foo" perl.com
my $var; $$variable_name perlmonks.org
open() or die $!; `$userinput` use.perl.org
use Modules; /$userinput/ perl.apache.org
parrotcode.org
FUNCTION RETURN LISTS
stat localtime caller SPECIAL VARIABLES
0 dev 0 second 0 package $_ default variable
1 ino 1 minute 1 filename $0 program name
2 mode 2 hour 2 line $/ input separator
3 nlink 3 day 3 subroutine $\ output separator
4 uid 4 month-1 4 hasargs $| autoflush
5 gid 5 year-1900 5 wantarray $! sys/libcall error
6 rdev 6 weekday 6 evaltext $@ eval error
7 size 7 yearday 7 is_require $$ process ID
8 atime 8 is_dst 8 hints $. line number
9 mtime 9 bitmask @ARGV command line args
10 ctime just use @INC include paths
11 blksz POSIX:: 3..9 only @_ subroutine args
12 blcks strftime! with EXPR %ENV environment
How to prevent XSS attacks through php?
There are a number of ways hackers put to use for XSS attacks, PHP’s built-in functions do not respond to all sorts of XSS attacks. Hence, functions such as strip_tags, filter_var, mysql_real_escape_string, htmlentities, htmlspecialchars, etc do not protect us 100%. You need a better mechanism, here is what is solution:
<?php function xss_clean($data) { // Fix &entity\n; $data = str_replace(array('&','<','>'), array('&amp;','&lt;','&gt;'), $data); $data = preg_replace('/(&#*\w+)[\x00-\x20]+;/u', '$1;', $data); $data = preg_replace('/(&#x*[0-9A-F]+);*/iu', '$1;', $data); $data = html_entity_decode($data, ENT_COMPAT, 'UTF-8'); // Remove any attribute starting with "on" or xmlns $data = preg_replace('#(<[^>]+?[\x00-\x20"\'])(?:on|xmlns)[^>]*+>#iu', '$1>', $data); // Remove javascript: and vbscript: protocols $data = preg_replace('#([a-z]*)[\x00-\x20]*=[\x00-\x20]*([`\'"]*)[\x00-\x20]*j[\x00-\x20]*a[\x00-\x20]*v[\x00-\x20]*a[\x00-\x20]*s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:#iu', '$1=$2nojavascript...', $data); $data = preg_replace('#([a-z]*)[\x00-\x20]*=([\'"]*)[\x00-\x20]*v[\x00-\x20]*b[\x00-\x20]*s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:#iu', '$1=$2novbscript...', $data); $data = preg_replace('#([a-z]*)[\x00-\x20]*=([\'"]*)[\x00-\x20]*-moz-binding[\x00-\x20]*:#u', '$1=$2nomozbinding...', $data); // Only works in IE: <span style="width: expression(alert('Ping!'));"></span> $data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?expression[\x00-\x20]*\([^>]*+>#i', '$1>', $data); $data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?behaviour[\x00-\x20]*\([^>]*+>#i', '$1>', $data); $data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:*[^>]*+>#iu', '$1>', $data); // Remove namespaced elements (we do not need them) $data = preg_replace('#</*\w+:\w[^>]*+>#i', '', $data); do { // Remove really unwanted tags $old_data = $data; $data = preg_replace('#</*(?:applet|b(?:ase|gsound|link)|embed|frame(?:set)?|i(?:frame|layer)|l(?:ayer|ink)|meta|object|s(?:cript|tyle)|title|xml)[^>]*+>#i', '', $data); } while ($old_data !== $data); // we are done... return $data; } ?> |
MYSQL data manipulation language (DML) commands?
Data Manipulation Language
Data Manipulation Language (DML) statements are used for managing data within tables. Some commands of DML are:
1. SELECT - retrieve data from the a database 2. INSERT - insert data into a table 3. UPDATE - updates existing data within a table 4. DELETE - deletes all records from a table, the space for the records remain 5. MERGE - UPSERT operation (insert or update) 6. CALL - call a PL/SQL or Java/php subprogram 7. LOCK TABLE - control concurrency |
MYSQL data definition language (DDL) commands?
Data Definition Language (DDL)
DDL statements are used to define and modify the database structure of your tables or schema. When you execute a DDL statement, it takes effect immediately.
Some commands of DDL are:
1. CREATE - to create table (objects) in the database 2. ALTER - alters the structure of the database 3. DROP - delete table from the database 4. TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed 5. COMMENT - add comments to the data dictionary 6. RENAME - rename a table |
How to backup and restore a MySQL database?
You can use mysqldump to create a simple backup of your database using the following syntax.
mysqldump -u [username] -p [password] [databasename] > [backupfile.sql] To Restore mysql -u [username] -p [password] [database_to_restore] < [backupfile] |
How to run perl in MAMP?
If everything is configured properly, put a perl file in your cgi-bin folder, set permissions so that apache can execute it, and you are all set ready to go.
Basically, Perl suffers in this aspect just because it was first and that is the way CGIs were done. PHP came along and the default setting allowed PHP scripts to run from any directory. So this is a little trouble for php programmers.
It took one hour for me to figure out how to run perl in MAMP.
Well here are some easy steps for you.
The permissions for all of those files needs to be 755.
Go to a Application >> Utility >> and open Terminal. cd /Applications/MAMP chmod 755 cgi-bin cd cgi-bin find . -type f -exec chmod 755 \{\} \; Put all perl files in cgi-bin folder. /Applications/MAMP/cgi-bin Run your script http://localhost/cgi-bin/test.pl You are done! |
How to include multiple js file in one js file?
To include multiple js files in page is bad in terms of http request. Yslow Yahoo! tool can give you bad grade. Grade F on making more HTTP requests.
Apart from that page loading time increases and page does not looks clean.
Combined files are a way to reduce the number of HTTP requests by combining all scripts into a single script, and similarly combining all CSS into a single stylesheet.
Including multiple .js file in one external file has several advantages.
1. Less HTTP request.
2. If cashing is on page lode faster.
3. Page looks clean.
Use this code to add as much as files as you want.
document.write('<script type="text/javascript" src="file1.js"></script>'); document.write('<script type="text/javascript" src="file2.js"></script>'); document.write('<script type="text/javascript" src="file3.js"></script>'); document.write('<script type="text/javascript" src="file4.js"></script>'); |
Is yahoo.com down?
Yes Yahoo.com is down today from 10/14/2010 1:54:22 PM
Still it is not up!
