PostgreSQL's libpq: Encoding for binary transport of ARRAY[]-data ?

Question

Hello,

after hours of documentations/boards/mailinglists and no progress I may ask you: How do I 'encode' my data to use it for binary transport using libpq's PQexecParams(.) ?

Simple variables are just in big endian order:

PGconn *conn;
PGresult *res;
char *paramValues[1];
int paramLengths[1];
int paramFormats[1];

conn = PQconnectdb(CONNINFO);

// -- (1) -- send a float value
float val_f = 0.12345678901234567890; // float precision: ~7 decimal digits
// alloc some memory & write float (in big endian) into
paramValues[0] = (char *) malloc(sizeof(val_f));
*((uint32_t*) paramValues[0]) = htobe32(*((uint32_t*) &val_f)); // host to big endian

paramLengths[0] = sizeof(val_f);
paramFormats[0] = 1; // binary

res = PQexecParams(conn, "SELECT $1::real ;", //
        1, // number parameters
        NULL, // let the backend deduce param type
        paramValues, //
        paramLengths, //
        paramFormats, //
        0); // return text
printf("sent float: %s \n", PQgetvalue(res, 0, 0));
// --> sent float: 0.123457

and like this also double, int, etc ...

But how about ARRAYs?

    float vals_f[] = {1.23, 9.87};
    // alloc some memory
    paramValues[0] = (char *) malloc(sizeof(float) * 2);

//  ???? paramValues[0] = ??????

    paramLengths[0] = sizeof(float) * 2;
    paramFormats[0] = 1; // binary


    res = PQexecParams(conn, "SELECT $1::real[] ;", //
            1, // number parameters
            NULL, // let the backend deduce param type
            paramValues, //
            paramLengths, //
            paramFormats, //
            0); // return text
    printf("sent float array: %s \n", PQgetvalue(res, 0, 0));

Is there any working example of transfering ARRAY data in PostgreSQL's binary format? The code in backend/utils/adt/ doesn't help me much (except I now know there is a ARRAYTYPE, but not how to use them) :-(

I just need a function char* to_PQbin(float [] input, int length) for passing to paramValues[.] ...

Thanks a lot, Tebas

PS: What is the suggested way of converting simple variables (rather than my htobe32(.))?