System Function NC

Monadic Function

Z←⎕NC R ⎕Name Classification.     Argument R should be a string, vector or matrix of workspace names to show names classes for.

R is   a character Scalar, Vector or character string Matrix   - to enumerate name classes for.

Z (returned) is a scalar or vector of name class results - e.g. a scalar or vector of integers.

System function ⎕NC takes as its right argument a character string specifying a name, vector of names, or character matrix of names. It returns a numeric result which is the classification of each name:
Z will contain:
1 = line label (if ⎕NC called from WITHIN a user function)
2 = variable (global variable name class, or if ⎕NC used IN a user function then local variable names class)
3 = function (for function name(s))
4 = operator
0 = name not in use
¯1 = invalid name

Examples, working with ⎕NC:

      )VARS        ⍝Show which global variables exists in the current NARS APL workspace
A B C              ⍝3 global variables names exist - A, B and C
      ⎕NC 3 2⍴'A B C '    ⍝Sample use of ⎕NC with a MATRIX right argument(3 names 'A ', 'B ' and 'C ' to enumerate/check)
2 2 2                     ⍝ 2 = global variable <--> all 3 names WERE FOUND.
      ⎕NC 3 1⍴'ABC'       ⍝Matrix right argument, compare to first call to ⎕NC, just above - {3 2⍴} vs {3 1⍴}
2 2 2                     ⍝Same correct results(2 2 2) = global variable names class
      ⎕NC ⊃'A ' 'B' 'B'  ⍝Call with a disclosed Nested Vector - note the extra space after variable named 'A' >> 'A '
2 2 2
      ⎕NC ⊃'A' 'B' 'C'   ⍝This call FAILS(returns 0=name not in use) because APL sees ⎕NC 'ABC'; there is NO variable named 'ABC'.
0                        ⍝ Name 'ABC' NOT FOUND
      ⎕NC ⊃'⍳ ' '⍴' 'A' 'ZZ'
¯1 ¯1 2 0      ⍝Names '⍳ ' and '⍴' are NOT validly constructed(¯1); Variable A IS Found(2), ZZ is validly constructed but Not Found(0).

⎕NC can be used to determine the presence(=2) or absence(=0) of an optional braced argument e.g. {L arg} FuncName R     argument in a user function call through ⎕NC usage WITHIN the user function itself, e.g. ⎕NC 'ArgName' ! Ref. User Defined Functions.
See also: Quad Name List ⎕NL

System Variables (A value may be assigned to these except for ⎕DM)
⎕ALX	⎕CT	⎕DM	⎕DT	⎕ELX	⎕FC	⎕FEATURE	⎕FPC	⎕IC	⎕IO
⎕LR	⎕LX	⎕PP	⎕PR	⎕PW	⎕RL	⎕SA	⎕WSID
Niladic System Functions (a value cannot be assigned to these)
⎕A	⎕AV	⎕EM	⎕ET	⎕LC	⎕NNAMES	⎕NNUMS	⎕SI	⎕SYSID	⎕SYSVER
⎕T	⎕TC	⎕TCBEL	⎕TCBS	⎕TCESC	⎕TCFF	⎕TCHT	⎕TCLF	⎕TCNL	⎕TCNUL
⎕TS	⎕WA
Monadic or dyadic system functions (a value cannot be assigned to these)
⎕AT	⎕CR	⎕DC	⎕DFT	⎕DL	⎕DR	⎕EA	⎕EC	⎕ERROR	⎕ES
⎕EX	⎕FMT	⎕FX	⎕MF	⎕NAPPEND	⎕NC	⎕NCREATE	⎕NERASE	⎕NINFO	⎕NL
⎕NLOCK	⎕NREAD	⎕NRENAME	⎕NREPLACE	⎕NRESIZE	⎕NSIZE	⎕NTIE	⎕NUNTIE	⎕STOP	⎕TF
⎕TRACE	⎕UCS	⎕VR
Note that quad functions and variables (except for the ⎕A family of functions) are case insensitive