Working of is_null() Function in PHP with Sample Code

Introduction to PHP is_null()

The PHP is_null() function is actually an in-built function of the PHP Programming Language which help us to find whether the variable is α NULL value or not. The PHP is_null() function works for PHP 4 and the above PHP versions which are introduced later after PHP 4 version. The type of the $variable_name parameter of the is_null() function is Boolean type value. Is_null() function of PHP accepts only one parameter and that too it is fully mandatory parameter. There are no optional parameters available inside of the is_null() PHP function.

Syntax:

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is_null( $variable_name )

Explanation of Parameter:

The is_null() function of PHP Programming Language usually accepts only one single parameter as mentioned in the above syntax.

  • $variable_name:The $variable name helps us to test whether the variable’s value is NULL or not. It is α mandatory parameter. There are no more optional parameters available inside of the is_null() function to mention.

Return value:

The is_null() function will return α Boolean value and the function is going to return TRUE only when the $variable_name is the NULL value, if the variable’s value is not NULL then it will return FALSE statement.

Working of is_null() Function in PHP

  • PHP is_null() function woks based on the NULL values present inside of the function’s parenthesis.
  • If the variable value inside of the is_null() function then the result will be TRUE and promotes the further conditions statement or any other.
  • If the variable’s value inside of the is_null() function is FALSE then statements which are inside of the those conditions will not be executed.
  • The value type of the PHP is_null() function is Boolean.
  • The only parameter of the is_null() function is α mixed type (mixed type means that it is going to indicate that the parameter has the capability of accepting the multiple types but not necessarily all types).
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Examples of PHP is_null()

Given below are the examples mentioned:

Example #1

In the below example, four variables is created with different variables and checked whether they are NULL values or not with the help of is_null() function of the PHP programming language. At first, $var11, $var12, $var13 and $var14 variables are created with different values for them. $var11 and $var13 variables are stored with “NULL” values. $var12 and $var14 values are stored with “ ” and 0 values. is considered as NULL but here it is assigned as α string value. Then “is_null() ? TRUE : FALSE” structured syntax is used to print the TRUE statements/others only if the is_null($variable_name) is TRUE. If not FALSE statement will be printed. Likewise the code implements the results below. Checking the $var11 and $var13 variable’s values using the is_null() function will print the TRUE value whereas for other variables ($var12 and $var14) the result will be FALSE value.

Syntax:

<?php
$var11 = NULL;
$var12 = " ";
$var13 = "NULL";
$var14 = 0;
is_null($var11) ?print_r("Null Value So Truen") : print_r("Falsen");
is_null($var12) ?print_r("Null Value So Truen") : print_r("Not Null so Falsen");
is_null($var13) ?print_r("Null Value So Truen") : print_r("Not Null so Falsen");
is_null($var14) ?print_r("Null Value So Truen") : print_r("Not Null so Falsen");
?>

Output:

php is_null() 1

Example #2

This is the example of demonstrating the working of the is_null() function of the PHP Programming Language. At first, α function “check_null1()” is created with only one parameter “$var11” in it. Inside of the function is_null() function is created to test whether the variable parameter of the function is TRUE or NOT. But here variable value of $var11 is not mentioned. Function is closed and called many times with different inputs. “NULL” is mentioned/passed to the $var11 by changing the capitalization of the NULL words as values. But for the last 3 echo statements, different values passed to the variable parameter of the function. So for the last echo statements the result will be FALSE.

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Syntax:

<?php
function check_null1($var11)
{
return (is_null($var11) ? "Null Value so :: True" : "Not Null Value so :: False");
}
echo check_null1(NULL) . "n";
echo check_null1(null) . "n";
echo check_null1(Null) . "n";
echo check_null1(NUll) . "n";
echo check_null1(NULl) . "n";
echo check_null1(nulL) . "n";
echo check_null1(nuLL) . "n";
echo check_null1(nULL) . "n";
echo check_null1('Nul') . "n";
echo check_null1(false) . "n";
echo check_null1(2). "n";
?>

Output:

check whether the variable parameter of the function is TRUE or NOT

Example #3

In the below example, $a1, $b1, $c1 and $d1 variables are created. NULL values are passed to $b1 and $d1 variables. Although “null” value is passed to the $c1 variable, but the NULL is passed as α string value. So the result of the $b1 and $d1 variable’s after checking with the is_null() function will be printed as empty value. For $a1 and $c1 variables, result will not all be print.

Syntax:

<?php
echo "For Non-NULL values the value will not be printed . Check Below :: n";
$a1 = 0;
echo "a1 is :: " . is_null($a1) . "n";
$b1 = null;
echo "b1 is :: " . is_null($b1) . "n";
$c1 = "null";
echo "c1 is :: " . is_null($c1) . "n";
$d1 = NULL;
echo "d1 is :: " . is_null($d1) . "n";
?>

Output:

php is_null() 3

Example #4

This is the example of checking for different $var11 variable’s values whether they are NULL or not. This is done by using different IF and ELSE conditions. At first, $var11 is stored with “TRUE” value and checked with the is_null() function so the ELSE condition result will be printed because the is_null(TRUE) function condition result is FALSE. Likewise for the second IF and ELSE condition, same result is printed. Then for the $var11 variable, “NULL” value is passed and then after checking with the is_null() function the result will show that “Variable var11 is NULL” like that.

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Syntax:

<?php
echo "Checking for TRUE value of the var11 variable for NULL :: n";
$var11 = TRUE;
if (is_null($var11))
{
echo 'Variable var11 is  NULL';
}
else
{
echo 'Variable var11 is not NULL';
}
echo "n";
echo "Checking for FALSE value of the var11 variable for NULL :: n";
$var11 = FALSE;
if (is_null($var11))
{
echo 'Variable var11 is  NULL';
}
else
{
echo 'Variable var11 is not NULL';
}
echo "n";
echo "Checking for NULL value of the var11 variable for NULL :: n";
$var11 = NULL;
if (is_null($var11))
{
echo 'Variable var11 is  NULL';
}
else
{
echo 'Variable var11 is not NULL';
}
echo "n";
?>

Output:

done by if and else condition

Conclusion

Here we saw introduction of PHP is_null() function with the syntax and it’s parameters explanation, working of PHP is_null() function along with various examples which involves is_null() function to understand the is_null() function well.

Recommended Articles

This is α guide to PHP is_null(). Here we discuss the introduction to PHP is_null() with respective examples for better understanding. You may also have α look at the following articles to learn more –

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