The USUPPLEMENTARY Function
The USUPPLEMENTARY function returns an integer value that is equal to the index of the first Unicode supplementary character
in a character string argument that is encoded in UTF-8 or UTF-16.
A Unicode supplementary character is a character above U+FFFF, that is, a character outside of the Basic Multilingual Plane (BMP). These characters are encoded in UTF-16 with a surrogate pair (two 16-bit code units), or are encoded in UTF-8 with a 4-byte representation.
The function type is integer.
General Format
Arguments
- argument-1
- Must be alphabetic, alphanumeric, or national.
argument-1 must contain valid UTF-8 or UTF-16 data based on its class:
- If argument-1 is of class alphabetic or alphanumeric, it must contain valid UTF-8 data.
- If argument-1 is of class national, it must contain valid UTF-16 data.
Returned Value
The returned value is an integer, which differs based on the argument-1 value:
- If the contents of argument-1 are not valid Unicode (UTF-8 or UTF-16, depending on class), the returned result is unpredictable.
- If argument-1 contains no supplementary characters, the returned value is zero.
- If argument-1 is of class alphabetic or alphanumeric, the returned value is the byte position of the first UTF-8 supplementary character in argument-1.
- If argument-1 is of class national, the returned value is the index, in UTF-16 encoding units, of the first UTF-16 supplementary character in argument-1.