PHP is_null() Function
PHP Available Functionsis_null()The function is used to check whether a variable is NULL.
PHP Version Requirement: PHP 4 >= 4.0.4, PHP 5, PHP 7
Syntax
bool is_null ( mixed $var )
Parameter description:
- $var: The variable to be checked.
Return Value
Returns TRUE if the specified variable is NULL, otherwise returns FALSE.
Example
Example
$var_name = TRUE;
$var_name2 = NULL;
if (is_null($var_name))
{
echo 'The variable var_name is NULL' . PHP_EOL;
}
else
{
echo 'The variable var_name is not NULL' . PHP_EOL;
}
if (is_null($var_name2))
{
echo 'The variable var_name2 is NULL' . PHP_EOL;
}
else
{
echo 'The variable var_name2 is not NULL' . PHP_EOL;
}
The output result is:
变量 var_name 不为 NULL 变量 var_name2 为 NULLOther Extensions