The KEYWORD_SET function returns a Boolean value based on the value of the specified expression. It returns a True (1) if its argument is defined and nonzero, and False (0) otherwise. The exact rules used to determine this are given in Return Value below.
Suppose that you are writing an IDL procedure that has the following procedure definition line:
PRO myproc, KEYW1 = keyw1, KEYW2 = keyw2
The following command could be used to execute a set of commands only if the keyword KEYW1 is set (i.e., it is present and nonzero):
IF KEYWORD_SET(keyw1) THEN BEGIN
The commands to be executed only if KEYW1 is set would follow.
Result = KEYWORD_SET(Expression)
This function returns True (1) if:
- Expression is a scalar or 1-element array with a non-zero value.
- Expression is a structure.
- Expression is an ASSOC file variable.
KEYWORD_SET returns False (0) if:
- Expression is undefined.
- Expression is a scalar or 1‑element array with a zero value.
The expression to be tested. Expression is usually a named variable.
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