This library contains various constants and functions for measuring time. These functions are useful for measuring the time consumption of programs.
// File time.h. // Interface of the library time. /////////////////////////////////////////////////////////// #ifndef _TIME_H #define _TIME_H #include <stddef.h> /////////////////////////////////////////////////////////// // Section 1 -- Time measurement /////////////////////////////////////////////////////////// typedef long time_t; // This function returns the reading of a wall clock, in // seconds. The function also assigns the reading of the // clock to the variable whose address is x (unless x is // NULL). Usage: instant = time (NULL); time_t time (time_t *x); #define CLOCKS_PER_SEC 1000000 typedef long clock_t; // The function clock returns the CPU time elapsed since // the beginning of the execution of your program. The time // is measured in cycles of the internal clock of your // computer. Each CLOCKS_PER_SEC cycles correspond // approximately to 1 second. Usage: // // double start, stop, elapsed; // start = (double) clock () / CLOCKS_PER_SEC; // . . . [computation] . . . // stop = (double) clock () / CLOCKS_PER_SEC; // elapsed = stop - start; // // Caution: After approximately 35 minutes, an arithmetic // overflow occurs. clock_t clock (void); #endif