Converts a time stored as a structure to a character string.

#include <time.h>

char *asctime (const struct tm *timedate);
errno_t asctime_s(char *string, rsize_t maxsize, const struct tm *timedate);

#include <wchar.h>

wchar_t *_wasctime(const struct tm *timedate);
errno_t _wasctime_s(wchar_t *string, rsize_t maxize, const struct tm *timedate);

Parameters

timedate

A pointer to a valid tm time/date structure, for example obtained using gmtime or localtime.

string

A pointer to a buffer to store the character string result. This function assumes a pointer to a valid memory location with a size specified by maxsize.

maxsize

The size of the buffer used to store the result, in characters.

Remarks

The asctime function converts a time stored as a structure to a character string. The _tm value is usually obtained from a call to gmtime or localtime. Both functions can be used to fill in a tm structure, as defined in TIME.H.

The converted character string is also adjusted according to the local time zone settings.

The converted string contains exactly 26 characters and has this form:

Wed Jan 02 02:03:55 1980\n\0

All elements have a constant width. The newline character \n and the null character \0 occupy the last two positions of the string.

This function uses a 24-hour clock.

The function uses a single statically allocated buffer to hold the return string. Each call destroys the result of the previous call.

Return Values

asctime and _wasctime: a pointer to the character string.

asctime_s and _wasctime_s: Zero if successful. If there is a failure a non-zero error code is returned. Any of the following conditions cause a failure and the function will return a value of EINVAL:

• string is a NULL Pointer
• maxsize is zero
•  0 < maxsize < 26 (in this case string is set to the empty string)
• timedate is a NULL pointer (in this case string is set to the empty string)
• Invalid timedata structure or values out of range (in this case string is set to the empty string)

Generic Text Routines

Requirements