clock_t clock ( void );

<ctime>

Clock program

Returns the number of clock ticks elapsed since the program was launched.

The macro constant expression CLOCKS_PER_SEC specifies the relation between a clock tick and a second (clock ticks per second).

The initial moment of reference used by clock as the beginning of the program execution may vary between platforms. To calculate the actual processing times of a program, the value returned by clock should be compared to a value returned by an initial call to clock.

Parameters

Return Value

On failure, the function returns a value of -1.

clock_t is a type defined in <ctime> to some type capable of representing clock tick counts and support arithmetical operations (generally a long integer).

Example

/* clock example: countdown */
#include <stdio.h>
#include <time.h>

void wait ( int seconds )
{
  clock_t endwait;
  endwait = clock () + seconds * CLOCKS_PER_SEC ;
  while (clock() < endwait) {}
}

int main ()
{
  int n;
  printf ("Starting countdown...\n");
  for (n=10; n>0; n--)
  {
    printf ("%d\n",n);
    wait (1);
  }
  printf ("FIRE!!!\n");
  return 0;
}

Output:

Starting countdown...
10
9
8
7
6
5
4
3
2
1
FIRE!!!

See also