null-pointer-p Function

Summary

Tests a pointer to see if it is a null pointer.

Package

fli

Signature

null-pointer-p pointer => result

Arguments

pointer⇩

A FLI pointer.

Values

result⇩

A boolean.

Description

The function null-pointer-p is used to determine if a pointer is a null pointer. A null pointer is a pointer pointing to address 0.

If pointer is a null pointer (that is, a pointer pointing to address 0) then result is true, otherwise null-pointer-p returns false.

Examples

In the following example a pointer to an :int is defined, and tested with null-pointer-p. The pointer is then freed, becoming a null pointer, and is once again tested using null-pointer-p.

(setq point (fli:allocate-foreign-object :type :int))

(fli:null-pointer-p point)

(fli:free-foreign-object point)

(fli:null-pointer-p point)

See also

3.2 Pointer testing functions
5.5.1.1 Testing whether a function is defined
*null-pointer*
pointer-address
pointer-eq