The typedef timeb_t refers to the following structure defined in the <timeb.h> header file: typedef struct timeb { time_t time; unsigned short millitm; short timezone; short dstflag; }; The member time gives the time in seconds. The member millitm gives the fractional time in milliseconds. After a call to ftime, the timezone and dstflag members of the timeb structure have the values of the global variables timezone and dstflag, respectively. See the description of the tzset function for timezone and dstflag global variables.