How do I set the timer in C?

#include

clock_t start,end;

int t;

Write at the beginning of the chronograph:

start = clock();

At the end of the chronograph write:

end = clock();

t=(end - start)/clocks_per_sec;

printf("you use % seconds", t);

clock() function:

clock() is a timing function in C C++, and the data type associated with it is clock t. In MSDN, the clock function is defined as follows:

clock_t

clock(void)

This function returns the CPU clock timing unit (clock) between the time "start this program process" and the time "the clock() function is called in the program".

tick), which is called a wall-clock in MSDN; If the wall clock time is not desirable, -1 is returned. where clock t is the data type used to store time, and in the file we can find the definition of it:

#ifndef

clock_t_defined

typedef

longclock_t;

#define

clock_t_defined

#endif

Obviously, clock t is a long integer number. In the file, a constant clocks per sec is also defined, which is used to indicate how many clock timing units there will be in a second, which is defined as follows:

#define

clocks_per_sec

clock_t)1000)

You can see that every thousandth of a second (1 millisecond), the value returned by calling the clock() function is increased by 1. As an example, you can use the formula clock() clocks per sec to calculate the runtime of a process itself

voidelapsed_time()

#include

#include

#include

intmain(void)

On the author's machine, the result is as follows:

timetodo

emptyloopsis

seconds

Above we saw that the length of the clock timing unit is 1 millisecond, so the accuracy of the timing is also 1 millisecond, so can we change the definition of clocks per sec by defining it larger, so that the timing accuracy is higher? Try it and you'll find that it doesn't work. In standard C++, the smallest unit of timekeeping is one millisecond.

time_t

time(time_t

The timer return value is the number of seconds from 1970 to the present.

It will be possible to connect it with a long type.

The same is true for parameters.

Such as longtime s

time_s

time(null

Time s is the number of seconds from 1970 to the present.

Or long

time_s

null;time(time_s);

Time s is the number of seconds from 1970 to the present.

If you want to calculate the period of time before and after, take the time once before, and subtract it once after that to know how many seconds it takes.