ALPHA-VISION® Compare Operations: IsNull

IsNull

SUMMARY

IsNull - checks for the argument to be false, equal null, an empty string, an uninitialized time value or not existing.

SYNTAX

IsNull(<arg>);

ARGUMENTS

arg (type:any)

IsNull can work on arbitrary arguments.

DESCRIPTION

1. Missing arguments are taken from the stack.(and removed from there).
2. The result is pushed onto the stack.

IsNull checks for the argument to be false, equal null, an empty string, an uninitialized time value or not existing.

EXAMPLES

///Stack before (1 Element):
//"abc"
IsNull();
//Stack afterwards: (1 Element):
//false
IsNull();
//Stack nachher: (1 Element):
//true //false is null

///Stack before is empty
IsNull();
//Stack afterwards: (1 Element):
//true

---

Syntax Notation

[aaa]

aaa is optional (zero or one occurences)

(aaa|bbb)

aaa exclusive or bbb

(aaa)*

aaa may occur indefinitely often or may be omitted

(aaa)+

aaa may occur indefinitely often but at least once

(aaa)m..n

aaa may occur from m to n times