» cidrnetmask Function

cidrnetmask converts an IPv4 address prefix given in CIDR notation into a subnet mask address.


prefix must be given in IPv4 CIDR notation, as defined in RFC 4632 section 3.1.

The result is a subnet address formatted in the conventional dotted-decimal IPv4 address syntax, as expected by some software.

CIDR notation is the only valid notation for IPv6 addresses, so cidrnetmask produces an error if given an IPv6 address.

» Examples

> cidrnetmask("")