Table of Contents

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

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.

FAQ- Time.H Header File In C With Examples

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