9.12. 網路位址函式及運算子
Table 9.36. cidr
andinet
Operators
Table 9.37shows the functions available for use with thecidr
andinet
types. Theabbrev
,host
, andtext
functions are primarily intended to offer alternative display formats.
Anycidr
value can be cast toinet
implicitly or explicitly; therefore, the functions shown above as operating oninet
also work oncidr
values. (Where there are separate functions forinet
andcidr
, it is because the behavior should be different for the two cases.) Also, it is permitted to cast aninet
value tocidr
. When this is done, any bits to the right of the netmask are silently zeroed to create a validcidr
value. In addition, you can cast a text value toinet
orcidr
using normal casting syntax: for example,inet(expression
)orcolname
::cidr.
shows the functions available for use with themacaddr
type. The functiontrunc(macaddr
)returns a MAC address with the last 3 bytes set to zero. This can be used to associate the remaining prefix with a manufacturer.
Themacaddr
type also supports the standard relational operators (>
,<=
, etc.) for lexicographical ordering, and the bitwise arithmetic operators (~
,&
and|
) for NOT, AND and OR.
Table 9.39shows the functions available for use with themacaddr8
type. The functiontrunc(macaddr8
)returns a MAC address with the last 5 bytes set to zero. This can be used to associate the remaining prefix with a manufacturer.
Themacaddr8
type also supports the standard relational operators (>
,<=
, etc.) for ordering, and the bitwise arithmetic operators (~
,and|
) for NOT, AND and OR.