Want more examples? Check out the official documentation. In the latter two examples, you can see that you can check the sub-properties of an object without first checking the parent properties – if any parent property is missing at any depth, isset() will return FALSE. Var-dump(isset($car->details->year)) // FAlSE as while the $car object has a 'details' property, the 'year' subproperty is NULL Var-dump(isset($car->details->colour)) // TRUE as the $car object has a 'details' property with a 'colour' subproperty, which has a value which is not NULL Var_dump(isset($car->wheels)) // FALSE as the $car object does not have a 'wheels' property Var_dump(isset($car->make)) // TRUE as the $car object has a 'make' property which is not NULL Just as isset() can be used to check if an array key is set, it can be used to check whether an object property is set: $car = (object) array('make' => 'ford', 'model' => 'fairlane', 'details' => array('colour' => 'blue', 'year' => NULL)) Example – Checking if an Object has an Attribute/Property I’m using the PHP var_dump() function to print out information on the return value from isset() – find out more here. A second look into the PHP specs tells that isnull() checks whether a value is null or not. Var_dump(isset($fruit_colours)) // FALSE as though $fruit_colours contains a value at the array key 'apples', the array stored at 'apples' doesn't contain a value at array key 'gala' Var_dump(isset($fruit_colours)) // TRUE as $fruit_colours contains a value at the array key 'apples', and the array stored at 'apples' has an array key with value 'macintosh' which is not NULL Var_dump(isset($fruit_colours)) // FALSE as though the array key 'lemons' is set, it has a value of NULL Var_dump(isset($fruit_colours)) // FALSE as the array key 'limes' does not exist inf the $fruit_colours array Var_dump(isset($fruit_colours)) // TRUE as the array key 'oranges' exists in the $fruit_colours array and is not NULL It can also check for deeper array values for multidimensional arrays: $fruit_colours = array('oranges' => 'orange', 'lemons' => NULL, 'apples' => array('granny_smith' => 'green', 'macintosh' => 'red')) Isset() can also be used to check whether a value is set for an array key or position in an array. } Example – Checking if an Element Exists in an Array Sometimes I receive empty results, like if the variable is null or empty, not even an empty space. send it via email or to a Google Spreadsheet). # The variable $var3 is not set, so isset() returned FALSE Im using isset to check if a variable is set and not null, then I process it (e.g. # The variable $var2 is set but has a NULL value, so isset() returned FALSE # The variable $var is set and is not NULL, so isset() returned TRUE Here is some simple example usage of the isset() function: $var = 1 FALSE if it is not set or has a value of NULL.It should be noted that they are not identical, though - when the array key exists but the value is null, isset will return false and arraykeyexists will return true. If this check is happening many thousands of times, youd want to use isset. Isset just checks if is it set, it could be anything not null. Between arraykeyexists and isset, though both are very fast O(1), isset is significantly faster.

At least one variable should be passed to isset() Empty checks if the variable is set and if it is it checks it for null, '', 0, etc.You can provide more variables, separated by commas.

Passing a value directly to isset() will result in an error – it must be a variable.

It can also be an array element or object attribute if you wish to check whether a value is set in an existing variable – see examples below.

Syntax for isset() isset ( $var1, $var2.) So, being able to check that a variable is set and is populated is pretty useful. You can’t perform actions on a variable that doesn’t exist or that has no value – you’ll either get unexpected output or an error. The following code might look like a bit of an overkill, but it is the most bulletproof solution I've found so far.This article shows you how to use the PHP isset() function to check whether a variable exists and is populated. The isset() function returns true if variable is set and not null. and if the object has that specific method/field. The isset() function will return true or false value. Before calling an object method, you have to check isint () - Informa se o tipo de uma variável. isfloat () - Verifica se a variável é do tipo float. isnumeric () - Verifica se uma variável é um número ou uma string numérica. isbool () - Verifica se a variável é um booleano. isbool () - Finds out whether a variable is a boolean. isset () - Determina se uma variável está declarada e é diferente de null. None of the other answers is fully correct, each one will only work in some cases. isset () - Determine if a variable is declared and is different than null.

Php isset check for null