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 a 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.
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Syntax:
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 check whether the variable’s value is NULL or not. It is a 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 a 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.
Given below are the examples mentioned:
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 $var14 values are stored with “\0” and 0 values. \0 is considered as NULL but here it is assigned as a string value. Then “is_null() ? TRUE : FALSE” structured syntax is used to print the TRUE statements/others only if the is_null($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.
Code:
<?php
$var11 = NULL;
$var12 = "\0";
$var13 = "NULL";
$var14 = 0;
is_null($var11) ?print_r("Null Value So True\n") : print_r("False\n");
is_null($var12) ?print_r("Null Value So True\n") : print_r("Not Null so False\n");
is_null($var13) ?print_r("Null Value So True\n") : print_r("Not Null so False\n");
is_null($var14) ?print_r("Null Value So True\n") : print_r("Not Null so False\n");
?>Output:
This is the example of demonstrating the working of the is_null() function of the PHP Programming Language. At first, a function “check_null1()” is created with only one parameter “$var11” in it. Inside of the function is_null() function is created to check 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 $var11 by changing the capitalization of the NULL words as values. But for the last 3 echo statements, different values passed to the variable parameter of the function. So for the last echo statements the result will be FALSE.
Code:
<?php
function check_null1($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:
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 a 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.
Code:
<?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:
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.
Code:
<?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:
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.
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