Web Technology Experts Notes

Saturday, 21 December 2019

What are special characters? and how to remove special characters?

Question: What are special characters?
Special characters are selected punctuation characters present on standard US keyboard.

Question: Provide list of special characters?

Character	Name
	Space
!	Exclamation
"	Double quote
#	Number sign (hash)
$	Dollar sign
%	Percent
&	Ampersand
'	Single quote
(	Left parenthesis
)	Right parenthesis
*	Asterisk
+	Plus
,	Comma
-	Minus
.	Full stop
/	Slash
:	Colon
;	Semicolon
<	Less than
=	Equal sign
>	Greater than
?	Question mark
@	At sign
[	Left bracket
\	Backslash
]	Right bracket
^	Caret
_	Underscore
`	Grave accent (backtick)
{	Left brace
\|	Vertical bar
}	Right brace
~	Tilde

Question: How to remove special characters from string including space?

$string='test !@#ing';
echo preg_replace('/[^A-Za-z0-9\-]/', '', $string);

Question: How to remove special characters from string except space?

$string='test !@#ing';
echo preg_replace('/[^A-Za-z0-9\-\s]/', '', $string);

Question: How to replace special characters with hyphen?

$string='test !@#ing';
echo preg_replace('/[^A-Za-z0-9\-\s]/', '-', $string);

Question: How to replace multiple hyphen with single hyphen?

$string='test-----ing';
echo preg_replace('/-+/', '-',$string);

Question: How to remove special characters from array?

$array=array('test !@#ing','sdalkjsad','#$#33');
function cleanData($string){
return preg_replace('/[^A-Za-z0-9\-]/', '', $string);
}
$array = array_map('cleanData',$array);
print_r($array);

Question: How to remove all special characters from javascript?

var stringToReplace='test !@#ing';
stringToReplace=stringToReplace.replace(/[^\w\s]/gi, '')

Monday, 16 December 2019

What is CPU Usage and Memory Usage?

CPU Usage- It is the "amount of time" a CPU was used for processing the given instructions.

Memory Usage- It is the "amount of RAM" was used for processing the given instructions

Entry Processes- It is number of scripts are running at a single time. One entry process take fraction of a second to complete. So in 10 entry process you can have 10-30 visitors.

Number of Processes- It is number of process(script) can run in one time. One process take time till the execution of script.

I/O Usage- It is speed of data transfer between the hard disk and the RAM.

Question: Is high CPU usage bad?
If the CPU usage is around 100%, this means that your computer is trying to do more work than it has the capacity. Always CPU usage must be less than 90%, If so increase the CPU.