### 8.2 `clock`—cumulative processor time

Synopsis

    #include <time.h>
    clock_t clock(void);

Description
Calculates the best available approximation of the cumulative amount of time used by your program since it started. To convert the result into seconds, divide by the macro `CLOCKS_PER_SEC`.

Returns
The amount of processor time used so far by your program, in units defined by the machine-dependent macro `CLOCKS_PER_SEC`. If no measurement is available, the result is (clock_t)`-1`.

Portability
ANSI C requires `clock` and `CLOCKS_PER_SEC`.

Supporting OS subroutine required: `times`.