Various time functions in c in time.h

I wrote a program in C for sorting using different algorithms.
I performed a timing mesurement experiment for each of the algorithms with different input sizes,

In order to measure timeing taken by each algorithm, I came across various C functions.
In this blog I am writing a broef summary of the functions I cam eacross. I am also mentioning some small examples to use eacf of these functions.

In C there are two main header files which have functions related To time, namely time.h and windows.h.

1.Time.h


A) The important datatypes associated with time.h are
1) time_t:  which is actually a 32/64 bit integer    ( __int32   / __int64)
2) size-t  which corresponds to the integral data type returned by the language operator sizeof and is defined in the<ctime> header file (among others) as an unsigned integral type.

B) The structure associated with manipulation of time is  tm. The structure as defined in time.h is :


 
struct tm {
        int tm_sec;     /* seconds after the minute - [0,59] */
        int tm_min;     /* minutes after the hour - [0,59] */
        int tm_hour;    /* hours since midnight - [0,23] */
        int tm_mday;    /* day of the month - [1,31] */
        int tm_mon;     /* months since January - [0,11] */
        int tm_year;    /* years since 1900 */
        int tm_wday;    /* days since Sunday - [0,6] */
        int tm_yday;    /* days since January 1 - [0,365] */
        int tm_isdst;   /* daylight savings time flag */
        };
C) Some of the important functions in time.h are:

1)  time

• Function headers:-time_t time ( time_t * timer );
• Description:-The function returns this value, and if the argument is not a null pointer, the value is                  also set to the object pointed by timer.
• Example:int main ()

  {
    time_t seconds;
  
    seconds = time (NULL);
    printf ("%ld hours since January 1, 1970", seconds/3600);
    
    return 0;
  }

2) difftime

• Function headers:double difftime ( time_t time2, time_t time1 );
• Description:It returns the diffrence between two times.  
• Example:int main ()

  {
    time_t start,end;
    char szInput [256];
    double dif;
  
    time (&start);
    printf ("Please, enter your name: ");
    gets (szInput);
    time (&end);
    dif = difftime (end,start);
    printf ("Hi %s.\n", szInput);
    printf ("It took you %.2lf seconds to type your name.\n", dif );
   
    return 0;

  }

3) mktime

• Function headers:time_t mktime ( struct tm * timeptr );
• Description:It converts the Convert tm structure to time_t 
• Example:

  int main () { time_t rawtime; struct tm * timeinfo; int year, month ,day; char * weekday[] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}; /* prompt user for date */ printf ("Enter year: "); scanf ("%d",&year); printf ("Enter month: "); scanf ("%d",&month); printf ("Enter day: "); scanf ("%d",&day); /* get current timeinfo and modify it to the user's choice */ time ( &rawtime ); timeinfo = localtime ( &rawtime ); timeinfo->tm_year = year - 1900; timeinfo->tm_mon = month - 1; timeinfo->tm_mday = day; /* call mktime: timeinfo->tm_wday will be set */ mktime ( timeinfo ); printf ("That day is a %s.\n", weekday[timeinfo->tm_wday]); return 0; }

2.Windows.h

A)Functions
B) Structure
C) Datatypes