sd_id128_to_string, sd_id128_from_string — Format or parse 128 bit IDs as strings
#include <systemd/sd-id128.h>
| char* sd_id128_to_string( | sd_id128_t id, char s[33] ); | 
| int sd_id128_from_string( | const char* s, sd_id128_t* ret ); | 
sd_id128_to_string()
                formats a 128 bit ID as character string. It expects
                the ID and a string array capable of storing 33
                characters. The ID will be formatted as 32 lowercase
                hexadecimal digits and be terminated by a NUL
                byte.
sd_id128_from_string()
                implements the reverse operation: it takes a 33
                character string with 32 hexadecimal digits
                (either lowercase or uppercase, terminated by NUL) and parses them back into an 128
                bit ID returned in
                ret. Alternatively, this call
                can also parse a 37 character string with a 128bit ID
                formatted as RFC UUID.
For more information about the
                sd_id128_t type see
                sd-id128(3). Note
                that these calls operate the same way on all
                architectures, i.e. the results do not depend on
                endianess.
When formatting a 128 bit ID into a string it is
                often easier to use a format string for
                printf(3). This
                is easily done using the
                SD_ID128_FORMAT_STR and
                SD_ID128_FORMAT_VAL() macros. For
                more information see
                sd-id128(3).
sd_id128_to_string() always
                succeeds and returns a pointer to the string array
                passed in.  sd_id128_from_string
                returns 0 on success (in which case
                ret is filled in), or a negative
                errno-style error code.
The sd_id128_to_string()
                and sd_id128_from_string() interfaces are
                available as shared library, which can be compiled and
                linked to with the libsystemd-id128
                pkg-config(1)
                file.