check if variable empty

Question

if   user id    NULL     user name    NULL     user logged    NULL         user id    -1        user name   NULL       user logged   NULL    if   user admin    NULL         user admin   NULL       Is there any shortest way to do it   And if i right  it should be tested with is null  It s possible  user id   user name and  user logged write in one line  maybe array   without repeating NULL

User · Accepted Answer

If you want to test whether a variable is really NULL, use the identity operator:

$user_id === NULL  // FALSE == NULL is true, FALSE === NULL is false
is_null($user_id)

If you want to check whether a variable is not set:

!isset($user_id)

Or if the variable is not empty, an empty string, zero, ..:

empty($user_id)

If you want to test whether a variable is not an empty string, ! will also be sufficient:

!$user_id

User · Answer

here i have explained how the empty function and isset works please use the one that is appropriate also you can use is null function also   lt  php      val   0        evaluates to true because  var is empty     if  empty  val             echo   val is either 0  empty  or not set at all               evaluates to true because  VAR IS SET     if  isset  val             echo   val is set even though it is empty               gt

User · Answer

Please define what you mean by  empty    The test I normally use is isset

User · Answer

Its worth noting - and I only found this out after nearly 9 years of PHP coding that the best way of checking any variable exists is using the empty   function  This is because it doesn t generate errors and even though you turn them off - PHP still generates them  empty   however won t return errors if the variable doesn t exist  So I believe the correct answer is not to check if its null but to do the following  if   empty  var   amp  amp  is null  var     Note the PHP manual      variable is considered empty if it does not exist or if its value equals FALSE   As opposed to being null which is handy here

User · Answer

lt  php   nothing   NULL   something        array   array 1 2 3       Create a function that checks if a variable is set or empty  and display   variable name is SET EMPTY  function  check  var        if  isset  var             echo  Variable is SET   PHP EOL      elseif  empty  var              echo  Variable is empty    PHP EOL              check  nothing   check  something   check  array

User · Answer

To check for null values you can use is null   as is demonstrated below   if  is null  value         value    MY TEXT     define to suit

User · Answer

1   if    user id     user name     user logged          do your stuff     2   No  I actually did not understand why you write such a construct   3   Put all values into array  for example  ar  user id    etc

User · Answer

you can use isset   routine    also additionaly you can refer an range of is type    functions like   is string    is float   is int   etc to further specificaly test

User · Answer

Felt compelled to answer this because of the other responses  Use empty   if you can because it covers more bases  Future you will thank me   For example  you will have to do things like isset    amp  amp  strlen    where instead you could use empty    Think of it like this empty is like  isset  var      var  false

User · Answer

The best and easiest way to check if a variable is empty in PHP is just to use the empty   function    if empty  variable  then

User · Answer

You can check if it s not set  or empty  in a number of ways   if    var       Or   if   var     null        This checks if the variable  by type  IS null    Or   if  empty  var        You can check if it s declared with   if   isset  var        Take note that PHP interprets 0  integer  and     empty string  and false as  empty  - and dispite being different types  these specific values are by PHP considered the same  It doesn t matter if  var is never set declared or if it s declared as  var   0 or  var       So often you compare by using the     operator which compares with respect to data type  If  var is 0  integer    var       or  var    false will validate  but  var        or  var     false will not

User · Answer

empty   is a little shorter  as an alternative to checking   user id as suggested elsewhere   if  empty  user id     empty  user name     empty  user logged

[php] check if variable empty

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