The C sizeof operator returns the size of a specified item in bytes. Because the datatype of its return value varies from platform to platform, specifying sizeof in place of a CS_INT argument to a Client-Library routine may result in a compiler error or warning if the type returned is not the same base type as CS_INT.
Client-Library provides the following macro to enable an application to use the sizeof function when calling Client-Library routines
CS_SIZEOF(variable) – casts a sizeof return value to CS_INT.
This macro is defined in the header file cstypes.h.