Home > Article > Backend Development > PHP function introduction—is_null(): Check whether the variable is null
PHP function introduction—is_null(): Check whether a variable is null
In PHP, is_null() is a commonly used function used to check whether a given variable is null. Null in PHP means that the variable has no value, that is, an empty value. The is_null() function can be used to easily determine whether a variable is null, and perform corresponding processing based on the judgment result.
The syntax of the is_null() function is:
bool is_null (mixed $var)
Among them, $var is the variable to be checked.
Let’s look at some examples of using the is_null() function:
Example 1: Determine whether the variable is null
8510a7fce94d9fa45939f302dd3a58e8
Through the is_null() function, we can determine whether the variable $name is null, the result is false, and output 0; determine whether the variable $age is null, the result is true, and output 1.
Example 2: Use is_null() function to process logic
e7f29a73c732611a64bc66168e387bb4
In the above example, we defined a function sayHello() that accepts a parameter $name. First, we use the is_null() function to determine whether $name is null. If it is null, output "Hello, stranger!"; otherwise, output "Hello, " plus the value of $name.
By using the is_null() function, we can perform corresponding logical processing based on whether the variable is null, increasing the flexibility and readability of the code.
Note:
0a3bae5a7bc4b1a8c337e976e28d38e2
f83f615ac7bf6402ce429908ea1c4b67
Summary:
The is_null() function is a very practical PHP function, used to determine whether a variable is null. Through it, you can easily perform null value judgment and perform corresponding logical processing based on the judgment result. In program development, appropriate use of the is_null() function can increase the readability and flexibility of the code, and improve the quality and maintainability of the code.
The above is the detailed content of PHP function introduction—is_null(): Check whether the variable is null. For more information, please follow other related articles on the PHP Chinese website!