Canonicalize CIDR: Difference between revisions

=={{header|REXX}}==

<lang rexx>/*REXX pgm canonicalizes IPv4 addresses that are in CIDR notation (dotted─dec/network).*/

parse arg z . /*obtain optional argument from the CL.*/

if z=='' | z=="," then z= '87.70.141.122/22' /*Not specified? Then use the default.*/

parse var z # '/' -0 mask /*get the address nodes & optional mask*/

#= translate(#, , .) /*elide periods from IPv4 address nodes*/

$= /*initialize the to-be reassembled IPv4*/

do j=1 for words(#); x= word(#, j) /*process each of the address nodes. */

if x//2 then x= x - 1 /*Is low─order bit on? Then remove it.*/

$= $ x /*reconstruct (by abutment) IPv4 nodes.*/

end /*j*/ /*(REXX stores it's numbers in decimal)*/

/*stick a fork in it, we're all done. */

say ' original IPv4 address: ' z /*display the original IPv4 address. */

say ' canonicalized address: ' translate( space($), ., " ") || mask /*canonicalized.*/</lang>

{{out|output|text=&nbsp; when using the default input:}}

<pre>

original IPv4 address: 87.70.141.122/22

canonicalized address: 86.70.140.122/22

</pre>