What are the functions of the gettype function in PHP?

The gettype() function in PHP is used to retrieve the type of a variable and returns a string representing that type. Its functionality includes:

1. To retrieve the basic type of a variable, you can use the gettype() function, which will return types such as integer, double, string, boolean, array, object, resource, or NULL.
2. Determine the variable type: You can use the gettype() function to determine the variable type, and then make conditional judgments or logical processing based on the returned string.
3. Differentiate between variables and constants: The gettype() function can distinguish between variables and constants, for constants, the gettype() function will return “constant”.
4. Differentiate between objects and arrays: To distinguish between objects and arrays, you can use the gettype() function. Objects will return “object” and arrays will return “array”.
5. Check resource type: To determine the type of a resource, use the gettype() function to retrieve the type of resource, such as file resource or database connection resource.
6. To check if a variable is empty, you can use the gettype() function to determine the variable’s type and check if it is NULL.

It is important to note that the types returned by the gettype() function in PHP are all in lowercase, such as “integer” or “string”.