What are the functions commonly used in php variables

Editor to share with you what the functions commonly used in php variables are, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Isset ():

Determine whether the variable exists. Return true if present, No flase

/ / isset (): check whether the variable exists $name = 'qingyu';$res= isset ($name); var_dump ($res); / / true$res2 = isset ($name,$age); var_dump ($res2); / / false$user_name = isset ($_ GET [' username'])? $_ GET ['username']:'; if (isset ($name)) {echo 'variable exists';} else {echo 'variable does not exist' } unset ():

Delete or destroy variables

/ / unset (): destroy the variable $name = 'qingyu';unset ($name); / / not only delete the variable, but also delete a value in the array echo $name; / / error if (isset ($name)) {echo' variable exists';} else {echo 'variable does not exist';} empty ():

Determine whether the variable is empty

Returns FALSE if var exists and is a non-empty, non-zero value, otherwise returns TRUE.

The following things are considered empty:

"" (empty string)

0 (0 as an integer)

0.0 (as 0 of a floating point number)

"0" (as 0 of the string)

NULL

FALSE

Array () (an empty array)

$var; (a variable that is declared but has no value)

/ / empty (): determine whether the variable is empty $name =''; if (empty ($name)) {echo'is empty'; / / empty} else {echo 'not empty';} echo ():

Output print values, not composite and special data type values.

Var_dump ():

Output print value, type, length, print composite or special type of data value.

/ / echo var_dump$age = 19 var_dump name = 'qingyu';echo $name,$age; / / qingyu 19$ arr = array; echo $arr; / / error var_dump ($age,$name,$arr). This is all of the article "what are the common functions of php variables?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!