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, including positional arguments left blank.

### 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.

### Examples

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


[Package base version 4.3.0 Index]