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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++ with the release of C++20 in std::chrono
.
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Example
The following C source code prints the current time to the standard output stream.
#include <stdio.h>
#include <stdlib.h>
#include <time.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)) {
fprintf(stderr, "Failure to obtain the current time.\n");
return EXIT_FAILURE;
}
// Convert to local time format.
c_time_string = ctime(¤t_time);
if (!c_time_string) {
fprintf(stderr, "Failure to convert the current time.\n");
return EXIT_FAILURE;
}
// Print to stdout. ctime() has already added a terminating newline character.
printf("Current time is %s", c_time_string);
return EXIT_SUCCESS;
}
The output is:
Current time is Thu Sep 15 21:18:23 2016
See also
References
External links
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