Just a short example C implementation of Oracle VARNUM/NUMBER type encoding, in case you could not use library functions. I didn’t found it anywhere when needed (and afterwards I found it doesn’t helps me at all due to little ‘problem’ in ora :() and Oracle documentation is pretty unclear about how-to do it.

typedef struct { uint8_t len; uint8_t exp; uint8_t man[20]; } VARNUM_t; static void setVARNUM(VARNUM_t *varnum, int64_t value) { int8_t digits = 0; uint64_t u_value = 0; /* init */ memset(varnum, 0, sizeof(*varnum)); varnum->len = 1; //start len /* check sign */ if(value >= 0) { u_value = value; varnum->exp = trunc(log(u_value) / log(100)) + 128 + 65; } else { u_value = value * - 1; varnum->exp = trunc(log(u_value) / log(100)) + 128 + 65; varnum->exp = ~varnum->exp; } /* count value digits */ digits = trunc(log(u_value) / log(10)); digits = ((digits / 2) + 1); /* mantisa */ for(; digits >= 0 && varnum->len <= 20; digits--) { uint64_t v_tmp = 0; /* prevent INT overflow for too much digits */ if(digits > 0) { uint64_t v_pow = powl(100, digits - 1); v_tmp = ((u_value / v_pow) / 100) % 100; } else v_tmp = u_value % 100; if(!v_tmp) continue; /* +1 for positive, subtract 101 for negative */ v_tmp = (value < 0 ? (101 - v_tmp) : (v_tmp + 1)); varnum->man[varnum->len - 1] = v_tmp; varnum->len++; } /* terminator byte for negative value */ if(value < 0 && varnum->len <= 20) { varnum->man[varnum->len - 1] = 102; varnum->len++; } return; }

NUMBER is just the same as VARNUM but without len member, thus is one byte shorter.

Note: this is just a quick implementation that works, there are some easy optimizations possible…