DHCP expression functions (index and substitution)
Glenn Satchell
glenn.satchell at uniq.com.au
Tue Jul 27 05:20:20 UTC 2010
Hi Chris
Check out the dhcp-eval man page. Some examples below:
On 07/27/10 11:23, Dorsey, Chris wrote:
> Is there a way to use the DHCP expression syntax to:
>
> 1) return the (n’th) character in a string.
substring (data-expr, offset, length)
foo = substring ( string, n, 1);
> 2) perform substring substitution within a given string.
This requires a bit of disassembly, then concat, eg if the substring to
be replaced is positions m to n:
pre = substring ( string, 1, m-1 );
post = substring ( string, n+1, 1000000 );
result = concat ( pre, "abcdef", post );
The 1000000 in substring returns the remaining chars up to the end of
the string (unless it is more than 1 million chars long). This can be
combined into one statement:
result = concat (
substring ( string, 1, m-1 ),
"abcdef",
substring ( string, n+1, 1000000 )
);
There are definitely other ways to do it.
> I’m thinking there has to be a way to do this, even though I don’t see
> ‘index()’ or ‘substitution()’ functions.
>
> tia,
> Chris
--
regards,
-glenn
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