Re: Sockets in RPGLE

On 01 Jun 1999, Scott Klement <infosys@klements.com> wrote:
>...  However,
>since the inet_addr function is designed for C programs, the string
>SHOULD be null-terminated.  (correct me if I'm wrong!)
>
>Therefore, my code would look like this:
>
>D inet_addr       PR            10I 0 ExtProc('inet_addr')
>D   DottedAddr                  16A
>
>C                   eval      TcpAddr = %trim(TcpAddr) + x'00'
>C                   eval      sin_addr = inet_addr(tcpAddr)
>...

This is right, but can be coded more easily if you are on V3R7 or greater
using a little-known parameter feature: OPTIONS(*STRING).

D inet_addr       PR            10I 0 ExtProc('inet_addr')
D   DottedAddr                    *   VALUE OPTIONS(*STRING)

C                   eval      sin_addr = inet_addr(%trim(tcpAddr))

Most "char *" parameters in C functions require null-terminated data.  You can
handle the null-termination yourself, or you can ask the RPG compiler to do it
for you using OPTIONS(*STRING) on a pointer parameter passed by value.  With
this type of parameter you can either pass a pointer or a character string.  If
a character string, the compiler creates a temporary with your value followed by
a null character, and passes that instead.

Left as an exercise for the keen student: check out the %STR bif to see how to
handle pointers to null-terminated data within your RPG program without scanning
for x'00' and substringing.

Barbara Morris


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