C++ time()

The time() function is defined in <ctime> header file.

time() prototype

time_t time(time_t* arg);

The time() function takes a pointer to time_t object as its argument and returns the current calendar time as a value of type time_t.

If arg is not a null pointer, the returned value is also stored in the object pointed to by arg.

time() Parameters

arg: pointer to a time_t object which (if not null) stores the time.

time() Return value

On success, the time() function returns the current calendar time as a value of type time_t.
On failure it returns -1 which is casted to type time_t.

Example 1: How time() function works with return value?

#include <ctime>
#include <iostream>
using namespace std;

int main()
{
	time_t current_time;

	current_time = time(NULL);
	cout << current_time << " seconds has passed since 00:00:00 GMT, Jan 1, 1970";

	return 0;
}

When you run the program, the output will be:

1489924627 seconds has passed since 00:00:00 GMT, Jan 1, 1970

Example 2: How time() function works with reference pointer?

#include <ctime>
#include <iostream>
using namespace std;

int main()
{
	time_t current_time;

        // Stores time in current_time
	time(&current_time);
	cout << current_time << " seconds has passed since 00:00:00 GMT, Jan 1, 1970";

	return 0;
}