N_TAGS

The N_TAGS function returns the number of structure tags contained in a structure expression. It optionally returns the size, in bytes, of the structure.

Calling Sequence

Result = N_TAGS( Expression )

Arguments

Expression

The expression for which the number of structure tags is to be returned. Expressions that are not of structure type are considered to have no tags. N_TAGS does not search for tags recursively, so if Expression is a structure containing nested structures, only the number of tags in the outermost structure are counted.

Keywords

LENGTH

Set this keyword to return the length of the structure, in bytes.

NOTE: The length of a structure is machine dependent. The length of a given structure will vary depending upon the host machine. IDL pads and aligns structures in a manner consistent with the host machine's C compiler.

Example

Find the number of tags in the system variable !P and print the result by entering:

PRINT, N_TAGS(!P)

Find the length of !P, in bytes:

PRINT, N_TAGS(!P, /LENGTH)