C++ date and time
In this article, we will learn about the date and time formats in C++. There is no complete format in C++ for date and time so we inherit it from the c language. To use date and time in c++, <ctime> header file is added in the program.
<ctime>
This header file has four time-related types as follows -
- Clock_t - It stands for clock type which is an alias of arithmetic type. It represents clock tick counts(units of a time of a constant with system-specific length). Clock_t is the type returned by clock()/.
- Time_t - It stands for time_type. It represents the time that is returned by function time(). It outputs an integral value as the number of seconds elapsed when time passes by 00:00 hours.
- Size_t - It is an alias for an unsigned integer type and represents the size of any object in bytes. Size_t is the result of the sizeof() operator which prints sizes and counts.
- tm - The tm structure holds date and time in the C structure. It is defined as follows -
Date and time functions in c++
| Name of the function |
Prototype of the function |
Description About the function |
| mktime |
time_t mktime(struct tm *time); |
This function converts mktime to time_t or calendar date and time. |
| ctime |
char *ctime(const time_t *time); |
It returns the pointer to a string of the format - day month year hours: minutes: seconds year. |
| difftime |
double difftime ( time_t time2, time_t time1 ); |
It returns the difference of two-time objects t1 and t2. |
| gmtime |
struct tm *gmtime(const time_t *time); |
This function returns the pointer of the time in the format of a structure. The time is in UTC. |
| clock |
clock_t clock(void); |
It returns an approximated value for the amount of time the calling program is being run. The value .1 is returned if not available. |
| localtime |
struct tm *localtime(const time_t *time); |
This function returns the pointer to the tm structure representing local time. |
| time |
time_t time(time_t *time); |
It represents current time. |
| strftime |
size_t strftime(); |
With the help of this function, we can format date and time in a specific manner. |
| asctime |
char * asctime ( const struct tm * time ); |
The function converts the type object of tm to string and returns the pointer to that string. |
Example to print current date and time
Below is the example to print the current date and time in the UTC format.
Code
Output
The local date and time is: Wed Sep 22 16:31:40 2021
The UTC date and time is: Wed Sep 22 16:31:40 2021
The below code tells how to break the tm structure and to print each attribute independently with the use of -> operator.
Code
Output
Number of seconds since January 1,2021 is:: 1632328553
Year:2021
Month: 9
Day: 22
Time: 21:65:53
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