Time.H Header File In C With Examples

Time.H Header File In C With Examples

The time.h header file in C contains functions for obtaining and manipulating date and time information. It introduces three time-related data types:

1. clock_t:

• Represents the processor time used by the program as an integer.
• It is a part of the calendar time, measuring the CPU time taken for the execution of a program.

2.time_t:

• Represents the calendar time as an integer.
• It is a part of the calendar time and is commonly used to store time values, often representing the number of seconds elapsed since a specific epoch.

3.struct tm:

• Holds the date and time information in a structured format.
• Contains members such as seconds, minutes, hours, day of the month, month, year, and more.
• Provides a convenient way to access and manipulate individual components of a date and time.

In summary, the time.h header file facilitates time-related operations in C programming, offering data types like clock_t and time_t for specific time representations, and struct tm for a structured approach to handling date and time information.

struct tm {
    // seconds,  range 0 to 59
    int tm_sec;
 
    // minutes, range 0 to 59
    int tm_min;
 
    // hours, range 0 to 23
    int tm_hour;
 
    // day of the month, range 1 to 31
    int tm_mday;
 
    // month, range 0 to 11
    int tm_mon;
 
    // The number of years since 1900
    int tm_year;
 
    // day of the week, range 0 to 6
    int tm_wday;
  // day in the year, range 0 to 365
    int tm_yday;
 
    // daylight saving time
    int tm_isdst;
}

This will have a CLOCKS_PER_SEC macro that will contain the number of times the system clock ticks per second.

Pre-defined functions in time.h

S.No	Function Name	Explanation
1.	asctime()	This function will returns the date and time in the format  day month date hours:minutes:seconds year. Eg: Sat Jul 27 11:26:03 2019. asctime() function returns a string by taking struct tm variable as a parameter.
2.	clock()	This function will returns the processor time consumed by a program
3.	ctime()	ctime() will return the date and time in the format day month hours:minutes:seconds year Eg: Sat Jul 27 11:26:03 2019 time is printed based on the pointer returned by Calendar Time
4.	difftime()	This function returns the difference between the time.
5.	gmtime()	This function will print the UTC (Coordinated Universal Time) Time and date. The format for both gmtime() and asctime() is the same.
6.	mktime()	This function will print the UTC (Coordinated Universal Time) Time and date. Format for both gmtime() and asctime() is the same.
7.	time()	This mktime() will returns the calendar-time equivalent using struct tm.
8.	strftime()	This strftime() will format the string returned by other time functions using different format specifiers

Example

1.Program to print the date and time of the system

#include <stdio.h>
#include <time.h>
int main(void)
{
    struct tm* ptr;
    time_t t;
    t = time(NULL);
    ptr = localtime(&t);
    printf("%s", asctime(ptr));
    return 0;
}

Output

Tue Aug  6 09:00:29 2019

  2. Program to print UTC (Coordinated Universal Time) of the system

#include <stdio.h>
#include <time.h>
int main(void)
{
    struct tm* ptr;
    time_t t;
    t = time(NULL);
    ptr = gmtime(&t);
    printf("%s", asctime(ptr));
    return 0;
}

Output

Tue Aug  6 09:00:31 2019

    3. Program to calculate the time taken to add two numbers program. 
             Note: If user gives input slowly that time also add up for total execution time. 

#include <stdio.h>
#include <time.h>
int main(void)
{
    time_t start, end;
    start = time(NULL);
    int a, b;
    scanf("%d %d", &a, &b);
    printf("Sum of %d and %d is %d\n",
           a, b, a + b);
    end = time(NULL);
    printf("Time taken to print sum is %.2f seconds",
           difftime(end, start));
}

Output

Sum of 4196144 and 0 is 4196144
Time taken to print sum is 0.00 seconds

4. Program to find the clock ticks

#include <math.h>
#include <stdio.h>
#include <time.h>
 
int frequency_of_primes(int n)
{
    // This function checks the number of
    // primes less than the given parameter
    int i, j;
    int freq = n - 1;
    for (i = 2; i <= n; ++i)
        for (j = sqrt(i); j > 1; --j)
            if (i % j == 0) {
                --freq;
                break;
            }
    return freq;
}
 
int main()
{
    clock_t t;
    int f;
    t = clock();
    f = frequency_of_primes(9999);
    printf("The number of primes lower"
           " than 10, 000 is: %d\n",
           f);
    t = clock() - t;
    printf("No. of clicks %ld clicks (%f seconds).\n",
           t, ((float)t) / CLOCKS_PER_SEC);
    return 0;
}

Output

The number of primes lower than 10, 000 is: 1229
No. of clicks 2837 clicks (0.002837 seconds).

5. Program to print time as hour: minute returned by asctime() file

#include <stdio.h>
#include <time.h>
int main()
{
    time_t rawtime;
    struct tm* timeinfo;
 
    // Used to store the time
    // returned by localetime() function
    char buffer[80];
 
    time(&rawtime);
    timeinfo = localtime(&rawtime);
    strftime(buffer, 80,
             "Time is %I:%M%p.",
             timeinfo);
 
    // strftime() function stores the
    // current time as Hours : Minutes
    //%I %M and %p-> format specifier
    // of Hours minutes and am/pm respectively*/
 
    // prints the formatted time
    puts(buffer);
  return 0;
}

Output

Time is 09:00AM.

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