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/length.html
length {base}R Documentation

Length of a Vector or List

Description

If x is (or can be coerced to) a vector or list, length returns the length of x. Otherwise, length returns NA.

The second form above can be used to reset the length of a vector. If a vector is shortened, extra values are discarded and when a vector is lengthened, it is padded out to its new length with NAs.

Usage

length(x)
length(x) <- n

Examples

length(diag(4))# = 16 (4 x 4)
length(options())# 12 or more..
length(y ~ x1 + x2 + x3)# 3
length(expression(x, {y <- x^2; y+2}, x^y)) # 3

[Package base version 0.90 ]