time.h header file in C with Examples - GeeksforGeeks

08 Jul, 2021
The time.h header file contains definitions of functions to get and manipulate date and time information.  
It describes three time-related data types. clock_t: clock_t represents the date as an integer which is a part of the calendar time.  time_t: time_t represents the clock time as an integer which is a part of the calendar time.  struct tm: struct tm holds the date and time which contains: 
clock_t: clock_t represents the date as an integer which is a part of the calendar time.  time_t: time_t represents the clock time as an integer which is a part of the calendar time.  struct tm: struct tm holds the date and time which contains: 
clock_t: clock_t represents the date as an integer which is a part of the calendar time.  
time_t: time_t represents the clock time as an integer which is a part of the calendar time.  
struct tm: struct tm holds the date and time which contains: 
C
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;}
It also contains CLOCKS_PER_SEC macro which holds the number of times does the system clock ticks per second.
Pre-defined functions in time.h 
Examples: Program to print the date and time of the system. 
Program to print the date and time of the system. 
Program to print the date and time of the system. 
C
#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;}
Tue Aug  6 09:00:29 2019
 
        2. Program to print UTC (Coordinated Universal Time) of the system. 
C
#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;}
 
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.  
C
#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));}
 
Sum of 4196144 and 0 is 4196144
Time taken to print sum is 0.00 seconds
 
       4. Program to find the clock ticks. 
C
#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;}
 
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.  
C
#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;}
 
Time is 09:00AM.
 
 
 
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