PHP | is_null() Function Last Updated : 05 Oct, 2021 Comments Improve Suggest changes Like Article Like Report The is_null() function is an inbuilt function in PHP which is used to find whether a variable is NULL or not. Syntax: boolean is_null ( $var ) Parameters: This function accepts a single parameter as shown in above syntax and described below. $var: Variable to check if it is NULL or not. Return value: It returns a boolean value. That is, it returns TRUE when $var will be NULL, otherwise it returns FALSE. Below programs illustrate the is_null() function in PHP: Program 1: PHP <?php // PHP code to demonstrate the working of is_null() function $var1 = NULL; $var2 = "\0"; // "\0" means "\0" $var3 = "NULL"; $var4 = 0; // $var1 has NULL value, so always give TRUE is_null($var1) ? print_r("True\n") : print_r("False\n"); // $var2 has '\0' value which consider as null in // c and c++ but here taken as string, gives FALSE is_null($var2) ? print_r("True\n") : print_r("False\n"); // $var3 has NULL string value so it will false is_null($var3) ? print_r("True\n") : print_r("False\n"); // $var4 is 0, gives FALSE is_null($var4) ? print_r("True\n") : print_r("False\n"); ?> Output: True False False False Program 2: PHP <?php // PHP code to demonstrate the working of // is_null() function function check_null($var) { return (is_null($var) ? "True" : "False"); } echo check_null(NULL) . "\n"; echo check_null(null) . "\n"; echo check_null(Null) . "\n"; echo check_null(NUll) . "\n"; echo check_null(NULl) . "\n"; echo check_null(nulL) . "\n"; echo check_null(nuLL) . "\n"; echo check_null(nULL) . "\n"; echo check_null(Nul) . "\n"; echo check_null(false) . "\n"; ?> Output: True True True True True True True True False False Reference: http://php.net/manual/en/function.is-null.php Comment More infoAdvertise with us Next Article PHP | is_null() Function M Mithun Kumar Follow Improve Article Tags : Misc Web Technologies PHP PHP-function Practice Tags : Misc Similar Reads PHP | is_link( ) Function The is_link() function in PHP used to check whether the specified file is a symbolic link or not. The path to the file is sent as a parameter to the is_link() function and it returns TRUE if the filename exists and is a symbolic link, otherwise it returns FALSE. Syntax: is_link(file) Parameters Used 2 min read PHP is_long() Function The is_long() function is an inbuilt function in PHP that is used to check whether the given value is a long integer or not. Syntax: bool is_long(mixed $value) Parameters: This function accepts a single parameter $value that holds the value which needs to check for a long integer. Return Value: This 1 min read PHP | is_numeric() Function The is_numeric() function is an inbuilt function in PHP which is used to check whether a variable passed in function as a parameter is a number or a numeric string or not. The function returns a boolean value. Syntax: bool is_numeric ( $var ) Parameters: The function accepts a single parameter which 2 min read PHP | is_a() function The is_a() is a built-in function in PHP and is used to check whether a given object is of a given class or not. It also checks if the given class is one of the parents of the given object or not. Syntax: boolean is_a($object, $class) Parameters: This function accepts two parameters as shown in the 2 min read PHP isset() Function The isset() function in PHP checks whether a variable is declared and not NULL. It returns true if the variable exists and has a non-NULL value, and false otherwise, without modifying the variable. Syntaxbool isset( mixed $var [, mixed $... ] )Parameters: This function accept one or more parameter a 3 min read Like