Caché ObjectScript Reference - InterSystems Documentation

$ZFZero-Terminated and Counted Unicode StringsThe $ZF function supports argument types for zero-terminated Unicode strings and countedUnicode strings. These are supported even in versions of Caché that do not use Unicodecharacters internally.The argument types for zero-terminated Unicode strings and counted Unicode strings havethe following codes:ArgumentwsPurposePointer to a zero-terminated Unicode character string.Pointer to a counted Unicode character string.For both argument types, the C data type of the Unicode character is an unsigned short. Apointer to a zero-terminated Unicode string is declared as follows:unsigned short *p;A pointer to a counted Unicode string is declared as a pointer to the following C structure:typedef struct zwarray {unsigned short len;unsigned short data[1]; /* 1 is a dummy value */} *ZWARRAYP;For example:ZWARRAYP *p;The len field contains the length of the Unicode character array.The data field contains the characters in the counted Unicode string. The maximum size ofa Unicode string is the maximum $ZF string size, which is an updateable configurationparameter that defaults to 32767.Each Unicode character is two bytes long. This is important to consider when declaringUnicode strings as output arguments, because Caché reserves space for the longest string thatmay be passed back. When using the default string size, the total memory consumption fora single Unicode string argument is calculated as follows:32767 maximum characters * 2 bytes per character = 65534 total bytes.This is close to the default maximum memory area allocated for all $ZF arguments, whichis 67584. This maximum $ZF heap area is also an updateable configuration parameter.Caché ObjectScript Reference 533