C/Development/Time Date

converts earth days into Jovian years

<source lang="cpp">

1. include <stdio.h>

int main(void) {

 float earth_days; /* number of earth days */
 float jovian_years; /* equivalent number of Jovian years */
 printf("Enter number of earth days: ");
 scanf("%f", &earth_days);
 jovian_years = earth_days / (365.0 * 12.0);
 printf("Equivalent Jovian years: %f", jovian_years);
 return 0;

}

      </source>

Convert time_t value to string: how to use ctime

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

int main () {

 time_t rawtime;
 time ( &rawtime );
 printf ( "Current date and time are: %s", ctime (&rawtime) );
 
 return 0;

}

      </source>

Convert time_t value to tm structure as UTC time: how to use gmtime

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>
3. define PST (-8)
4. define CET (1)
5. define BJ (8)

int main () {

 time_t rawtime;
 struct tm *p;
 time ( &rawtime );
 p = gmtime ( &rawtime );
 printf ("Time in Los Angeles: %2d:%02d\n", p->tm_hour+PST, p->tm_min);
 printf ("Time in Berlin:      %2d:%02d\n", p->tm_hour+CET, p->tm_min);
 printf ("Time in Bei Jing:   %2d:%02d\n", p->tm_hour+BJ, p->tm_min);
 
 return 0;

}

      </source>

Convert time_t value to tm structure in local time: How to use localtime

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

int main () {

 time_t rawtime;
 struct tm *tminfo;
 time ( &rawtime );
 tminfo = localtime ( &rawtime );
 printf ( "Current date and time are: %s", asctime (tminfo) );
 
 return 0;

}

      </source>

Convert tm structure to string: how to use asctime

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

int main () {

 time_t rawtime;
 struct tm *timeinfo;
 time ( &rawtime );
 timeinfo = localtime ( &rawtime );
 printf ( "Current date and time are: %s", asctime (timeinfo) );
 
 return 0;

}

      </source>

Convert tm structure to time_t value: how to use mktime

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

int main () {

 time_t rawtime;
 struct tm *timeinfo;
 int year = 2005, month = 2 ,day = 2;
 
 char * weekday[] = { "Sunday", "Monday",
                      "Tuesday", "Wednesday",
                      "Thursday", "Friday", "Saturday"};
 
 /* get current timeinfo and modify it to 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;

}

      </source>

Create local time from time()

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

int main(void) {

 struct tm *ptr;
 time_t lt;
 char str[80];
 lt = time(NULL);
 ptr = localtime(&lt);
 strftime(str, 100, "It is now %H %p.", ptr);
 printf(str);
 return 0;

}

      </source>

Display a date

<source lang="cpp">

1. include <stdio.h>

void main() {

 int month = 0;
 int day = 0;
 int year = 0;
 printf("Enter the date as three integer values separated by spaces (month day year):\n");
 scanf("%d", &month);
 scanf("%d", &day);
 scanf("%d", &year);
 if(day>3 && day<21 || day>23 && day<31)
   printf("\n%dth ",day);
 else
   printf("\n%d%s ", day, (day%10 == 1 ? "st": (day%10 == 2 ? "nd" : "rd")));
 switch(month)
 {
   case 1:
     printf("January ");
     break;
   case 2:
     printf("February ");
     break;
   case 3:
     printf("March ");
     break;
   case 4:
     printf("April ");
     break;
   case 5:
     printf("May");
     break;
   case 6:
     printf("June");
     break;
   case 7:
     printf("July");
     break;
   case 8:
     printf("August");
     break;
   case 9:
     printf("September");
     break;
   case 10:
     printf("October");
     break;
   case 11:
     printf("November");
     break;
   case 12:
     printf("December");
     break;
 }
 printf(" %d\n", year);

}

      </source>

Get current time: how to use time and time_t

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

int main () {

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

}

      </source>

Get the elapsed time: clock and CLOCKS_PER_SEC

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

int main(void) {

 printf("Elapsed time: %u secs.\n", clock()/CLOCKS_PER_SEC);

 return 0;

}

      </source>

Get time: how to use time() and time_t

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

int main(void) {

 time_t lt;
 lt = time(NULL);
 printf(ctime(&lt));
 return 0;

}

      </source>

Get time: now

<source lang="cpp">

1. include <stdio.h> /* For input and output */
2. include <time.h> /* For time() and clock() functions */

void main() {

  long time_taken = clock();    
   
  printf("%ld\n", time_taken);
  printf("%d\n", CLOCKS_PER_SEC);
  
  
}

      </source>

Getting date data with ease

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

void main() {

 char *Day[7] = {
                  "Sunday"  , "Monday", "Tuesday", "Wednesday",
                  "Thursday", "Friday", "Saturday"
                };
 char *Month[12] = {
                    "January",   "February", "March",    "April",
                    "May",       "June",     "July",     "August",
                    "September", "October",  "November", "December"
                   };
 char *Suffix[] = { "st", "nd", "rd", "th" };
 int i = 3;                                
 struct tm *OurT = NULL;                   
 time_t Tval = 0;
 Tval = time(NULL);
 OurT = localtime(&Tval);
 switch( OurT->tm_mday )
 {
   case 1: case 21: case 31:
     i= 0;                  /* Select "st" */
     break;
   case 2: case 22:
     i = 1;                 /* Select "nd" */
     break;
   case 3: case 23:
     i = 2;                 /* Select "rd" */
     break;
   default:
     i = 3;                 /* Select "th" */
     break;
 }
 printf("\nToday is %s the %d%s %s %d", Day[OurT->tm_wday],
     OurT->tm_mday, Suffix[i], Month[OurT->tm_mon], 1900 + OurT->tm_year);
 printf("\nThe time is %d : %d : %d",
                                     OurT->tm_hour, OurT->tm_min, OurT->tm_sec );

}

      </source>

Getting the time as a string

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>
3. include <string.h>
4. define TIME_24 1
5. define TIME_12 0

char *get_time_string(int mode24); /* Returns the time as a string in 12 or 24 hour format */ int main() {

 char time_str[12];
 get_time_string(TIME_24);
 printf("\n\n");
 get_time_string(TIME_12);

} char* get_time_string(int mode24) {

 static char time_str[12] = {0};   /* Stroes the time as a string */
 struct tm *now = NULL;
 int hour = 0;
 time_t time_value = 0;
 time_value = time(NULL);          /* Get time value              */
 now = localtime(&time_value);     /* Get time and date structure */
 hour = now->tm_hour;              /* Save the hour value         */
 if(!mode24 && hour>12)            /* Adjust if 12 hour format    */
   hour -= 12;
 printf("%d:",hour);
 printf("%d:",now->tm_min);
 printf("%d",now->tm_sec);

 if(!mode24)
   if(now->tm_hour>24){
      printf("PM\n");
   }else{
      printf("AM\n");
    }
 return time_str;

}

      </source>

How to check the performance: difftime

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

int main(void) {

 time_t start,end;
 volatile long unsigned t;
 start = time(NULL);
 for(t = 0; t < 5000000; t++) 
     ;
 end = time(NULL);
 
 printf("Loop used %f seconds.\n", difftime(end, start));
 return 0;

}

      </source>

How to get local time: localtime and asctime

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

int main(void) {

 struct tm *ptr;
 time_t lt;
 lt = time(NULL);
 ptr = localtime(&lt);
 printf(asctime(ptr));
 return 0;

}

      </source>

Local time and Coordinated Universal Time and date

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

/* Print local and UTC time. */ int main(void) {

 struct tm *local, *gm;
 time_t t;
 t = time(NULL);
 
 local = localtime(&t);
 
 printf("Local time and date: %s\n", asctime(local));
 
 gm = gmtime(&t);
 
 printf("Coordinated Universal Time and date: %s", asctime(gm));
 return 0;

}

      </source>

Make time: hour, minute, second, year, day, month

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

int main(void) {

 struct tm t;
 time_t t_of_day;
 t.tm_year = 2005-1900;
 t.tm_mon = 0;
 t.tm_mday = 3;
 t.tm_hour = 0;  /* hour, min, sec don"t matter */
 t.tm_min = 0;   /* as long as they don"t cause a */
 t.tm_sec = 1;   /* new day to occur */
 t.tm_isdst = 0;
 t_of_day = mktime(&t);
 printf(ctime(&t_of_day));
 return 0;

}

      </source>

Print local and UTC time

<source lang="cpp">

1. include <time.h>
2. include <stdio.h>

int main(void) {

 struct tm *local;
 time_t t;
 t = time(NULL);
 local = localtime(&t);
 printf("Local time and date: %s\n", asctime(local));
 local = gmtime(&t);
 printf("UTC time and date: %s\n", asctime(local));
 return 0;

}

      </source>

Return difference between two times: how to use difftime

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

int main () {

 time_t start, end;
 char str[256];
 double dif;
 time (&start);
 printf ("Please, enter your name: ");
 gets (str);
 time (&end);
 
 dif = difftime (end, start);
 
 printf ("You have taken %.2lf seconds to type your name.\n", dif );

 return 0;

}

      </source>

Return number of clock ticks since process start

<source lang="cpp">

1. include <stdio.h>
2. include <time.h>

void wait ( int seconds ) {

 clock_t endwait;
 endwait = clock () + seconds * CLK_TCK ;
 
 while (clock() < endwait) {
 }

} int main () {

 int i;
 printf ("Starting count down...\n");
 
 for (i = 20; i > 0; i--) {
   printf (" i = %d\n",i);
   wait (1);
 }
 
 printf ("Done!!!\n");
 
 return 0;

}

      </source>