C Reference function clock()

Usage of clock():

clock_t clock ( void );

Parameters:

None.

Return Value:

The number of clock ticks elapsed since the program start. If the function fails then it will return a value of -1. The clock_t type is defined in ctime.h.

Explanation:

The function returns the number of clock ticks elapsed since the start of the program.

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

Note:The initial moment of reference used by clock as the beginning of the program on different platforms.

Source code example of clock():

	#include <stdio.h>
	#include <time.h>

	void sec_wait ( int sec )
	{
		clock_t wait_till_end;
		wait_till_end = clock () + sec * CLOCKS_PER_SEC ;
		while (clock() < wait_till_end) {} 	} 	int main () 	{ 		int i; 		printf ("Starting countdown...\n"); 		for (i=10; i>0; i--)
		{
			printf ("%d\n",i);
			sec_wait (1);
			if ( i == 3 )
				printf ("Engine started...\n");
		}
		printf ("and lift off....\n");
		return 0;
	}

Output example of the program above:

	Starting countdown...
	10
	9
	8
	7
	6
	5
	4
	3
	Engine started...
	2
	1
	And lift off....