C++ Program to Print Date and Time

In this article, you will learn and get code to print date and time in default and custom format using C++ program. Here are the list of programs available in this article:

Print Current Date and Time in Default Format
Print Date in DD-MM-YYYY Format
Print Time in HH:MM:SS Format
Print Date/Time in Custom Format

Print Current Date & Time in Default Format

This program prints current date and time in default format. The question is, write a program in C++ to print date and time. Here is its answer:

#include<iostream>
#include<ctime>
using namespace std;
int main()
{
    time_t tmNow = time(0);
    char *dt = ctime(&tmNow);
    cout<<"Current Date/Time: "<<dt;
    cout<<endl;
    return 0;
}

This program was build and run under Code::Blocks IDE. Here is its sample output:

As you can see that, this program produces the current local date and time in default format. Here is the snapshot, shows local date/time in my computer system right now (at the same time while executing the above program):

In this program, the time_t is not a primitive (primary) data type. It is defined to store system's time value. The system's time values are returned from time(), a standard library function. So the following C++ statement:

time_t tmNow = time(0);

initializes the number of seconds elapsed since 00:00 hours, Jan 1, 1970 UTC. That is, after executing the above statement, the variable, tmNow holds total number of seconds elapsed since 1^st January 1970. The value of seconds from that time to now is 1608536102 approximately

If you convert this number of seconds into years, then here are step-by-step conversion:

1608536102 seconds = (1608536102/60) minutes
                   = 26808935 minutes
                   = (26808935/60) hours
                   = 446815 hours
                   = (446815/24) days
                   = 18617 days
                   = (18617/365.24) years
                   = 50.97 years

So if we add 50.97 years to 1970, we'll get 1970+50.97 or 2020.97. That is almost equal to 2021. The date when this program is executed, 21 Dec, 2020

Note - To satisfy this condition, we've added 1970 to the year in every program given below.

Note - To understand why I've divided by 365.24 instead of 365 to convert days into years, refer to Leap Year Formula Explained to get every required thing about the topic.

The function ctime() returns a string that represents the local time. This function is defined in ctime header file

Print Current Date in DD-MM-YYYY Format

Because previous program prints date in default format, therefore let's print the date first in our required format. Later on, I've also created a program to print time in custom format.

#include<iostream>
#include<ctime>
using namespace std;
int main()
{
    time_t tmNow;
    tmNow = time(NULL);
    struct tm t = *localtime(&tmNow);
    cout<<"Current Date: "<<t.tm_mday<<"-"<<t.tm_mon+1<<"-"<<t.tm_year+1900;
    cout<<endl;
    return 0;
}

Here is its sample output:

In above program, the function localtime() returns the local time of system. It is defined in ctime header file. It accepts a parameter that represents the pointer to time_t object. And returns a pointer to a struct tm object. Now using the structure, the object tm can access the following data members:

tm_mday
tm_mon
tm_year

Note - Since by default, 0 indicates January, therefore I've added 1 to tm_mon before printing the month number.

Print Current Time in HH:MM:SS Format

Now let's print the time in HH:MM:SS format. Here the HH indicates hours, MM indicates minutes, and SS indicates seconds

#include<iostream>
#include<ctime>
using namespace std;
int main()
{
    time_t tmNow;
    tmNow = time(NULL);
    struct tm t = *localtime(&tmNow);
    cout<<"Current Time: "<<t.tm_hour<<":"<<t.tm_min<<":"<<t.tm_sec;
    cout<<endl;
    return 0;
}

The snapshot given below shows the sample output produced by this program:

Print Current Date/Time in Custom Format

This is the last program that format the date in custom form. That is, we've used switch() case to match and print the month name instead of month number.

#include<iostream>
#include<ctime>
using namespace std;
int main()
{
    time_t tmNow;
    tmNow = time(NULL);
    struct tm t = *localtime(&tmNow);
    int mon;
    cout<<"Today's Date: "<<t.tm_mday<<" ";
    mon = t.tm_mon+1;
    switch(mon)
    {
        case 1:
            cout<<"Jan, ";
            break;
        case 2:
            cout<<"Feb, ";
            break;
        case 3:
            cout<<"Mar, ";
            break;
        case 4:
            cout<<"Apr, ";
            break;
        case 5:
            cout<<"May, ";
            break;
        case 6:
            cout<<"June, ";
            break;
        case 7:
            cout<<"July, ";
            break;
        case 8:
            cout<<"Aug, ";
            break;
        case 9:
            cout<<"Sept, ";
            break;
        case 10:
            cout<<"Oct, ";
            break;
        case 11:
            cout<<"Nov, ";
            break;
        case 12:
            cout<<"Dec, ";
            break;
    }
    cout<<t.tm_year+1900;
    cout<<"\nToday's Time: ";
    if(t.tm_hour>=12)
    {
        if(t.tm_hour==12)
            cout<<"12";
        else
            cout<<t.tm_hour-12;
        cout<<":"<<t.tm_min<<":"<<t.tm_sec<<" PM";
    }
    else
        cout<<t.tm_hour<<":"<<t.tm_min<<":"<<t.tm_sec<<" AM";
    cout<<endl;
    return 0;
}