The clock type represent clock ticks counts and can be used for arithmetical operations.

The clock type clock_t is returned by the clock function of time.h header file.
It represents the number of clock ticks since the program was started.

Usage of strftime():

size_t strftime ( char * ptr_dest, size_t maxsize, const char * format, const struct tm * ptr_time );

Parameters:

ptr_dest is a pointer to the destination array where the resulting C string is copied too.

The maxsize contains the maximum number of characters to be copied to ptr_dest. More »

Usage of localtime():

struct tm * localtime ( const time_t * ptr_time );

Parameters:

The pointer ptr_time is a pointer to a time_t object that contains a calendar time.

Return Value:

The function localtime() returns a pointer to a tm structure. The tm structure contains the time information.

Explanation:

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Usage of gmtime():

struct tm * gmtime ( const time_t * ptr_time);

Parameters:

The pointer ptr_time is a pointer to a time_t object that contains a calendar time.
Calendar time is the number of seconds that have elapsed since EPOCH, which is 00:00:00, January 1, 1970 Universal Coordinate Time (UTC)

Return Value:

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Usage of ctime():

char * ctime ( const time_t * ptr_time );

Parameters:

Pointer ptr_time to a time_t object that contains a calendar time.

Return Value:

The function returns a C string containing the date and time information.
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Usage of asctime():

char * asctime ( const struct tm * ptr_time );

Parameters:

ptr_time is a pointer to a tm structure which in turn contains a calendar time.

Return Value:

The function returns a C string containing the date and time information.
The string is followed by a new-line character (‘\n’) and the terminating null-character. More »