Oracle C++ Call Interface Programmer's Guide

External Datatypes
is not an integer, the fractional part is discarded, and no error is returned. If the
number to be returned exceeds the capacity of an unsigned integer for the operating
system, Oracle returns an overflow on conversion error.
VARCHAR
The external datatype VARCHAR store character strings of varying length. The first
two bytes contain the length of the character string, and the remaining bytes contain
the actual string. The specified length of the string in a bind or a define call must
include the two length bytes, meaning the largest VARCHAR string is 65533 bytes
long, not 65535. For converting longer strings, use the LONG VARCHAR external
datatype.
VARCHAR2
The external datatype VARCHAR2 is a variable-length string of characters up to 4000
bytes.
VARNUM
The external datatype VARNUM is similar to the external datatype NUMBER, except
that the first byte contains the length of the number representation. This length
value does not include the length byte itself. Reserve 22 bytes to receive the longest
possible VARNUM. You must set the length byte when you send a VARNUM value to
the database.
Table 4–4 VARNUM Examples
Decimal
Value
Length
Byte
Exponent
Byte Mantissa Bytes
0 1 128 N/A N/A
5 2 193 6 N/A
-5 3 62 96 102
2767 3 194 28, 68 N/A
-2767 4 61 74, 34 102
100000 2 195 11 N/A
1234567 5 196 2, 24, 46, 68 N/A
Terminator
Byte
Datatypes 4-19