<h2>Overview</h2>

`CLOCKS_PER_SEC` is a macro in C language and is defined in the `<time.h>` header file. It is an expression of type, ﻿as shown below﻿:

```C
 clock_t clock(void)
```
`CLOCKS_PER_SEC` defines the number of clock ticks per second for a particular machine. The number of seconds elapsed since ﻿the launch of a program can be calculated with the following formula:
$$seconds = \frac{clock ticks}{CLOCKS\_PER\_SEC}$$

<h2>Example</h2>

`CLOCKS_PER_SEC` is always used in combination with the `clock()` function. Below is an example of how you can use the macro `CLOCKS_PER_SEC` to calculate ﻿the seconds ﻿that have passed since a program was launched:

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

int main(){
  clock_t start, end;
  int i;

  start = clock();
  
  printf("Clock ticks at starting time: %ld\n", start);
  for(i=0; i< 1000000000; i++){
  }
  end = clock();
  printf("Clock ticks at end time: %ld\n", end);
  

  printf("CLOCKS_PER_SEC: %ld\n", CLOCKS_PER_SEC);
  printf("The duration in seconds since the program was launched: %ld\n", (end-start)/CLOCKS_PER_SEC);
  
  return 0;
}

What is CLOCKS_PER_SEC in C?

CLOCKS_PER_SEC in C, defined in <time.h>, indicates clock ticks per second for timing calculations.