Time related functions
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Time functions in C
are used to interact with system time routine and formatted time outputs
are displayed. Example programs for the time functions are given below.
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| S.no |
Function
|
Description
|
| 1 |
setdate() |
This function used to modify the system date |
| 2 |
getdate() |
This function is used to get the CPU time |
| 3 |
clock() |
This function is used to get current system time |
| 4 |
time() |
This function is used to get current system time as structure |
| 5 |
difftime() |
This function is used to get the difference between two given times |
| 6 |
strftime() |
This function is used to modify the actual time format |
| 7 |
mktime() |
This function interprets tm structure as calendar time |
| 8 |
localtime() |
This function shares the tm structure that contains date and time informations |
| 9 |
gmtime() |
This function shares the tm structure that contains date and time informations |
| 10 |
ctime() |
This function is used to return string that contains date and time informations |
| 11 |
asctime() |
Tm structure contents are interpreted by this function as calendar time. This time is converted into string. |
Example program for setdate() function in C:
This function is used to modify the system date.
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#include<stdio.h>
#include<dos.h>
#include<conio.h>
int main()
{
struct date dt;
printf("Enter new date in the format(day month year)");
scanf("%d%d%d",&dt.da_day,&dt.da_mon,&dt.da_year);
setdate(&dt);
printf("Now, current system date is %d-%d-%d\n"
,dt.da_day,dt.da_mon,dt.da_year);
return 0;
}
|
Output:
Enter new date in the format(day month year)
01 12 2012
Now, current system date is 01-12-2012
|
Example program for getdate() function in C:
This function is used to get the CPU time.
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#include<stdio.h>
#include<dos.h>
int main()
{
struct date dt;
getdate(&dt);
printf("Operating system's current date is %d-%d-%d\n"
,dt.da_day,dt.da_mon,dt.da_year);
return 0;
}
|
Output:
| Operating system’s current date is 12-01-2012 |
Example program for clock() function in C:
This function is used to get current system time
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#include <stdio.h>
#include <time.h>
#include <math.h>
int main()
{
int i;
clock_t CPU_time_1 = clock();
printf("CPU start time is : %d \n", CPU_time_1);
for(i = 0; i < 150000000; i++);
clock_t CPU_time_2 = clock();
printf("CPU end time is : %d", CPU_time_2);
}
|
Output:
| CPU start time is : 0
CPU end time is : 380000 |
Example program for time() function in C:
This function is used to get current system time as structure
|
|
#include <stdio.h>
#include <time.h>
int main ()
{
time_t seconds;
seconds = time (NULL);
printf ("Number of hours since 1970 Jan 1st " \
"is %ld \n", seconds/3600);
return 0;
}
|
Output:
| Number of hours since 1970 Jan 1st is 374528 |
Example program for difftime() function in C:
This function is used to get the difference between two given times
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#include <stdio.h>
#include <time.h>
int main()
{
time_t begin,end;
long i;
begin= time(NULL);
for(i = 0; i < 150000000; i++);
end = time(NULL);
printf("for loop used %f seconds to complete the " \
"execution\n", difftime(end, begin));
return 0;
}
|
Output:
| for loop used 15.000000 seconds to complete the execution |
Example program for strftime(), asctime() and localtime() in C:
- strftime() - This function is used to modify the actual time format.
- asctime() – tm structure contents are interpreted by asctime() function as calendar time. This time is converted into string.
- localtime() – This function shares the tm structure that contains date and time informations.
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#include <stdio.h>
#include <time.h>
#define LEN 150
int main ()
{
char buf[LEN];
time_t curtime;
struct tm *loc_time;
//Getting current time of system
curtime = time (NULL);
// Converting current time to local time
loc_time = localtime (&curtime);
// Displaying date and time in standard format
printf("%s", asctime (loc_time));
strftime (buf, LEN, "Today is %A, %b %d.\n", loc_time);
fputs (buf, stdout);
strftime (buf, LEN, "Time is %I:%M %p.\n", loc_time);
fputs (buf, stdout);
return 0;
}
|
Output:
Sat Sep 22 01:15:03 2012
Today is Saturday, Sep 22.
Time is 01:15 AM. |
Example program for mktime() and ctime() functions in C:
- mktime() function interprets tm structure as calendar time.
- ctime() function is used to return string that contains date and time informations.
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#include <stdio.h>
#include <time.h>
int main()
{
struct tm strtime;
time_t timeoftheday;
strtime.tm_year = 2008-1900;
strtime.tm_mon = 1;
strtime.tm_mday = 4;
strtime.tm_hour = 02;
strtime.tm_min = 30;
strtime.tm_sec = 38;
strtime.tm_isdst = 0;
timeoftheday = mktime(&strtime);
printf(ctime(&timeoftheday));
return 0;
}
|
Output:
Example program for gmtime() function in C:
This function shares the tm structure that contains date and time informations.
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#include <stdio.h>
#include <time.h>
int main()
{
time_t orig_format;
time(&orig_format);
printf ("Universal Time is %s",
asctime(gmtime(&orig_format)));
return 0;
}
|
Output:
| Universal Time is Sat Sep 22 08:11:40 2012 |
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