C date and time functions

The C date and time functions are a group of functions in the standard library of the C programming language implementing date and time manipulation operations. They provide support for time acquisition, conversion between date formats, and formatted output to strings.
Overview of functions.
The C date and time operations are defined in the codice_1 header file (codice_2 header in C++).
The and related types were originally proposed by Markus Kuhn to provide a variety of time bases, but only was accepted. The functionalities were, however, added to C++ in 2020 in std::chrono.
Example.
The following C source code prints the current time to the standard output stream.
int main(void)
 time_t current_time;
 char* c_time_string;
 /* Obtain current time. */
 current_time = time(NULL);
 if (current_time == ((time_t)-1))
 (void) fprintf(stderr, "Failure to obtain the current time.\n");
 exit(EXIT_FAILURE);
 /* Convert to local time format. */
 c_time_string = ctime(&current_time);
 if (c_time_string == NULL)
 (void) fprintf(stderr, "Failure to convert the current time.\n");
 exit(EXIT_FAILURE);
 /* Print to stdout. ctime() has already added a terminating newline character. */
 (void) printf("Current time is %s", c_time_string);
 exit(EXIT_SUCCESS);
The output is:
Current time is Thu Sep 15 21:18:23 2016