how to use clock in c code example

Example: C clock

/** A working clock of time and date
   that using your own computer's
   local time to run the clock
   without setting the time and date
   in the code itself.               **/

//C libraries statement
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

//Programming the delay command
void delay(int secondsNumber)
{
	int milliSecondsNumber = 1000 * secondsNumber;
	clock_t startTime = clock();
	while(clock() < startTime + milliSecondsNumber);
}

//Driver program
int main(void)
{
	//Declaring the variable
	char buff[100];
	
	//Making the clock run forever
	for(; ;)
	{
		//Seting the clock over your computer local time
		time_t now = time(0);
		strftime(buff, 100, " %H:%M.%S \n %d/%m/%Y", localtime(&now));
		
		//Cleaning the command line and printing the clock
		system("cls");
		printf("\n %s\n", buff);
		
		//Seting a delay of one second between each print
		delay(1);
	}
}

///The code itself without the details:

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

void delay(int numOfSec)
{
	int numOfMilliSec = 1000 * numOfSec;
	clock_t startTime = clock();
	while(clock() < startTime + numOfMilliSec);
}

int main(void)
{
	char buff[100];
	
	for(; ;)
	{
		time_t now = time(0);
		strftime(buff, 100, " %H:%M.%S \n %d/%m/%Y", localtime(&now));
		
		system("cls");
		printf("\n %s\n", buff);
		
		delay(1);
	}
}