A pointer to a foreign string.
An external format specification.
The length of the string to convert.
t, it is assumed the string terminates with a null character. The default value for null-terminated-p is
A boolean. The default is false.
convert-from-foreign-string, given a pointer to a foreign string, converts the foreign string to a Lisp string. The pointer does not need to be of the correct type, as it will automatically be coerced to the correct type as specified by external-format.
The external-format argument is interpreted as by with-foreign-string. The names of available external formats are listed in the section "External formats" in the LispWorks User Guide and Reference Manual .
Either length or null-terminated-p must be non-nil. If null-terminated-p is true and length is not specified, it is assumed that the foreign string to be converted is terminated with a null character.
Section "External formats" in the LispWorks User Guide and Reference Manual
Modifying a string in a C function
Mapping Nil to a Null Pointer
LispWorks Foreign Language Interface User Guide and Reference Manual - 29 Sep 2017