Why check both isset and empty

Question

Is there a difference between isset and  empty  If I do this double boolean check  is it correct this way or redundant  and is there a shorter way to do the same thing   isset  vars 1   AND  empty  vars 1

User · Answer

It is not necessary      No warning is generated if the variable does not exist  That means   empty   is essentially the concise equivalent to  isset  var      var      false    php net

User · Answer

Empty just check is the refered variable array has an value if you check the php doc empty  you ll see this things are considered emtpy          an empty string    0  0 as an integer     0   0 as a string    NULL   FALSE   array    an empty array    var  var   a variable declared  but without a value in a class     while isset check if the variable isset and not null which can also be found in the php doc isset

User · Answer

The accepted answer is not correct   isset   is NOT equivalent to  empty     You will create some rather unpleasant and hard to debug bugs if you go down this route  e g  try running this code    lt  php   s        print  isset       isset  s           print   empty        empty  s            gt    https   3v4l org J4nBb

User · Answer

From the PHP Web site  referring to the empty   function    Returns FALSE if var has a non-empty and non-zero value   That   s a good thing to know  In other words  everything from NULL  to 0 to        will return TRUE when using the empty   function    Here is the description of what the isset   function returns    Returns TRUE if var exists  FALSE otherwise   In other words  only variables that don   t exist  or  variables with strictly NULL values  will return FALSE on the isset   function  All variables that have any type of value  whether it is 0  a blank text string  etc  will return TRUE

User · Answer

if we use same page to add edit via submit button like below   lt input type  hidden  value   lt  echo   GET  edit id     gt   name  edit id  gt    then we should not use   isset   POST  edit id      bcoz edit id is set all the time whether it is add or edit page   instead  we should use  check below condition    empty   POST  edit id

User · Answer

isset   tests if a variable is set and not null   http   us php net manual en function isset php  empty   can return true when the variable is set to certain values   http   us php net manual en function empty php  To demonstrate this  try the following code with  the var unassigned  set to 0  and set to 1    lt  php    the var   0   if  isset  the var       echo  set     else     echo  not set      echo   n    if  empty  the var       echo  empty     else     echo  not empty       gt

User · Answer

a   0  if  isset  a        a is set because it has some value  eg 0     echo   a has value     if   empty  a        a is empty because it has value 0     echo   a is not empty     else       echo   a is empty

User · Answer

isset  vars 1   AND  empty  vars 1   is equivalent to  empty  vars 1     I prepared simple code to show it empirically   Last row is undefined variable    ----------- --------- --------- ---------- ---------------------    Var value   empty     isset      empty     isset    amp  amp   empty      ----------- --------- --------- ---------- ---------------------                true      true      false      false                               false     true      true       true                    false       true      true      false      false                   true        false     true      true       true                    array       true      true      false      false                   NULL        true      false     false      false                    0          true      true      false      false                   0           true      true      false      false                   0 0         true      true      false      false                   undefined   true      false     false      false                  ----------- --------- --------- ---------- ---------------------    And code   var1        var2         var3   FALSE   var4   TRUE   var5   array     var6   null   var7    0    var8   0   var9   0 0   function compare  var        print var export  var  true                  var export empty  var   true                  var export isset  var   true                  var export  empty  var   true                  var export isset  var   amp  amp   empty  var   true      n       for   i   1   i  lt   9   i           var    var     i      compare   var       print var export  var10  true              var export empty  var10   true              var export isset  var10   true              var export  empty  var10   true              var export isset  var10   amp  amp   empty  var10   true      n      Undefined variable must be evaluated outside function  because function itself create temporary variable in the scope itself

User · Answer

Empty   only works on variables  Empty can mean different things for different variable types  check manual  http   php net manual en function empty php     isset   checks if the variable exists and checks for a true NULL or false value  Can be unset by calling  unset   Once again  check the manual   Use of either one depends of the variable type you are using    I would say  it s safer to check for both  because you are checking first of all if the variable exists  and if it isn t really NULL or empty

User · Answer

This is completely redundant  empty is more or less shorthand for  isset  foo       foo  and  empty is analogous to isset  foo   amp  amp   foo  I e  empty does the reverse thing of isset plus an additional check for the truthiness of a value     Or in other words  empty is the same as   foo  but doesn t throw warnings if the variable doesn t exist  That s the main point of this function  do a boolean comparison without worrying about the variable being set   The manual puts it like this      empty   is the opposite of  boolean  var  except that no warning is generated when the variable is not set    You can simply use  empty  vars 1   here

[php] Why check both isset() and !empty()

Examples related to php