# nargs

0th

Percentile

##### The Number of Arguments to a Function

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

Keywords
programming
##### Usage
nargs()
##### Details

The count includes empty (missing) arguments, so that foo(x,,z) will be considered to have three arguments (see ‘Examples’). This can occur in rather indirect ways, so for example x[] might dispatch a call to [.some_method(x, ) which is considered to have two arguments.

This is a primitive function.

##### References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

args, formals and sys.call.
library(base) # NOT RUN { tst <- function(a, b = 3, ...) {nargs()} tst() # 0 tst(clicketyclack) # 1 (even non-existing) tst(c1, a2, rr3) # 3 foo <- function(x, y, z, w) { cat("call was ", deparse(match.call()), "\n", sep = "") nargs() } foo() # 0 foo(, , 3) # 3 foo(z = 3) # 1, even though this is the same call nargs() # not really meaningful # }