This help topic is for R version 0.90. For the current version of R, try https://stat.ethz.ch/R-manual/R-patched/library/base/html/nargs.html
nargs {base}R Documentation

The Number of Arguments to a Function

Description

When used inside a function body, nargs returns the number of arguments supplied to that function.

Usage

nargs()

See Also

args, formals and sys.call.

Examples

tst <- function(a, b=3, ...) {nargs()}
tst() # 0
tst(clicketyclack) # 1 (even non existing)
tst(c1,a2,rr3) # 3

nargs()# not really meaningful

[Package base version 0.90 ]