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C date and time functions
Library of C programs From Wikipedia, the free encyclopedia
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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.[1] They provide support for time acquisition, conversion between date formats, and formatted output to strings.
History
The format string used in strftime
traces back to at least PWB/UNIX 1.0, released in 1977. Its date
system command includes various formatting options.[2][3] In 1989, the ANSI C standard is released including strftime
and other date and time functions.[4]
Overview of functions
Summarize
Perspective
The C date and time operations are defined in the time.h
header file (ctime
header in C++).
The timespec
and related types were originally proposed by Markus Kuhn to provide a variety of time bases, but only TIME_UTC
was accepted.[6] The functionalities were, however, added to C++ in 2020 in std::chrono.
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Example
The following C source code prints the current time to the standard output stream.
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
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(¤t_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
See also
References
External links
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