newlib-cygwin/newlib/libc/time/strftime.c

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2000-02-18 03:39:52 +08:00
/*
* strftime.c
* Original Author: G. Haley
*
* Places characters into the array pointed to by s as controlled by the string
* pointed to by format. If the total number of resulting characters including
* the terminating null character is not more than maxsize, returns the number
* of characters placed into the array pointed to by s (not including the
* terminating null character); otherwise zero is returned and the contents of
* the array indeterminate.
*/
/*
FUNCTION
<<strftime>>---flexible calendar time formatter
INDEX
strftime
ANSI_SYNOPSIS
#include <time.h>
size_t strftime(char *<[s]>, size_t <[maxsize]>,
const char *<[format]>, const struct tm *<[timp]>);
TRAD_SYNOPSIS
#include <time.h>
size_t strftime(<[s]>, <[maxsize]>, <[format]>, <[timp]>)
char *<[s]>;
size_t <[maxsize]>;
char *<[format]>;
struct tm *<[timp]>;
DESCRIPTION
<<strftime>> converts a <<struct tm>> representation of the time (at
<[timp]>) into a string, starting at <[s]> and occupying no more than
<[maxsize]> characters.
You control the format of the output using the string at <[format]>.
<<*<[format]>>> can contain two kinds of specifications: text to be
copied literally into the formatted string, and time conversion
specifications. Time conversion specifications are two-character
sequences beginning with `<<%>>' (use `<<%%>>' to include a percent
sign in the output). Each defined conversion specification selects a
field of calendar time data from <<*<[timp]>>>, and converts it to a
string in one of the following ways:
o+
o %a
An abbreviation for the day of the week.
o %A
The full name for the day of the week.
o %b
An abbreviation for the month name.
o %B
The full name of the month.
o %c
A string representing the complete date and time, in the form
. Mon Apr 01 13:13:13 1992
o %d
The day of the month, formatted with two digits.
o %H
The hour (on a 24-hour clock), formatted with two digits.
o %I
The hour (on a 12-hour clock), formatted with two digits.
o %j
The count of days in the year, formatted with three digits
(from `<<001>>' to `<<366>>').
o %m
The month number, formatted with two digits.
o %M
The minute, formatted with two digits.
o %p
Either `<<AM>>' or `<<PM>>' as appropriate.
o %S
The second, formatted with two digits.
o %U
The week number, formatted with two digits (from `<<00>>' to `<<53>>';
week number 1 is taken as beginning with the first Sunday in a year).
See also <<%W>>.
o %w
A single digit representing the day of the week: Sunday is day <<0>>.
o %W
Another version of the week number: like `<<%U>>', but counting week 1
as beginning with the first Monday in a year.
o
o %x
A string representing the complete date, in a format like
. Mon Apr 01 1992
o %X
A string representing the full time of day (hours, minutes, and
seconds), in a format like
. 13:13:13
o %y
The last two digits of the year.
o %Y
The full year, formatted with four digits to include the century.
o %Z
Defined by ANSI C as eliciting the time zone if available; it is not
available in this implementation (which accepts `<<%Z>>' but generates
no output for it).
o %%
A single character, `<<%>>'.
o-
RETURNS
When the formatted time takes up no more than <[maxsize]> characters,
the result is the length of the formatted string. Otherwise, if the
formatting operation was abandoned due to lack of room, the result is
<<0>>, and the string starting at <[s]> corresponds to just those
parts of <<*<[format]>>> that could be completely filled in within the
<[maxsize]> limit.
PORTABILITY
ANSI C requires <<strftime>>, but does not specify the contents of
<<*<[s]>>> when the formatted string would require more than
<[maxsize]> characters.
<<strftime>> requires no supporting OS subroutines.
*/
#include <stddef.h>
#include <stdio.h>
#include <time.h>
static _CONST int dname_len[7] =
{6, 6, 7, 9, 8, 6, 8};
static _CONST char *_CONST dname[7] =
{"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"};
static _CONST int mname_len[12] =
{7, 8, 5, 5, 3, 4, 4, 6, 9, 7, 8, 8};
static _CONST char *_CONST mname[12] =
{"January", "February", "March", "April",
"May", "June", "July", "August", "September", "October", "November",
"December"};
size_t
_DEFUN (strftime, (s, maxsize, format, tim_p),
char *s _AND
size_t maxsize _AND
_CONST char *format _AND
_CONST struct tm *tim_p)
{
size_t count = 0;
int i;
for (;;)
{
while (*format && *format != '%')
{
if (count < maxsize - 1)
s[count++] = *format++;
else
return 0;
}
if (*format == '\0')
break;
format++;
switch (*format)
{
case 'a':
for (i = 0; i < 3; i++)
{
if (count < maxsize - 1)
s[count++] =
dname[tim_p->tm_wday][i];
else
return 0;
}
break;
case 'A':
for (i = 0; i < dname_len[tim_p->tm_wday]; i++)
{
if (count < maxsize - 1)
s[count++] =
dname[tim_p->tm_wday][i];
else
return 0;
}
break;
case 'b':
for (i = 0; i < 3; i++)
{
if (count < maxsize - 1)
s[count++] =
mname[tim_p->tm_mon][i];
else
return 0;
}
break;
case 'B':
for (i = 0; i < mname_len[tim_p->tm_mon]; i++)
{
if (count < maxsize - 1)
s[count++] =
mname[tim_p->tm_mon][i];
else
return 0;
}
break;
case 'c':
if (count < maxsize - 24)
{
for (i = 0; i < 3; i++)
s[count++] =
dname[tim_p->tm_wday][i];
s[count++] = ' ';
for (i = 0; i < 3; i++)
s[count++] =
mname[tim_p->tm_mon][i];
sprintf (&s[count],
" %.2d %2.2d:%2.2d:%2.2d %.4d",
tim_p->tm_mday, tim_p->tm_hour,
tim_p->tm_min,
tim_p->tm_sec, 1900 +
tim_p->tm_year);
count += 17;
}
else
return 0;
break;
case 'd':
if (count < maxsize - 2)
{
sprintf (&s[count], "%.2d",
tim_p->tm_mday);
count += 2;
}
else
return 0;
break;
case 'H':
if (count < maxsize - 2)
{
sprintf (&s[count], "%2.2d",
tim_p->tm_hour);
count += 2;
}
else
return 0;
break;
case 'I':
if (count < maxsize - 2)
{
if (tim_p->tm_hour == 0 ||
tim_p->tm_hour == 12)
{
s[count++] = '1';
s[count++] = '2';
}
else
{
sprintf (&s[count], "%.2d",
tim_p->tm_hour % 12);
count += 2;
}
}
else
return 0;
break;
case 'j':
if (count < maxsize - 3)
{
sprintf (&s[count], "%.3d",
tim_p->tm_yday + 1);
count += 3;
}
else
return 0;
break;
case 'm':
if (count < maxsize - 2)
{
sprintf (&s[count], "%.2d",
tim_p->tm_mon + 1);
count += 2;
}
else
return 0;
break;
case 'M':
if (count < maxsize - 2)
{
sprintf (&s[count], "%2.2d",
tim_p->tm_min);
count += 2;
}
else
return 0;
break;
case 'p':
if (count < maxsize - 2)
{
if (tim_p->tm_hour < 12)
s[count++] = 'A';
else
s[count++] = 'P';
s[count++] = 'M';
}
else
return 0;
break;
case 'S':
if (count < maxsize - 2)
{
sprintf (&s[count], "%2.2d",
tim_p->tm_sec);
count += 2;
}
else
return 0;
break;
case 'U':
if (count < maxsize - 2)
{
sprintf (&s[count], "%2.2d",
(tim_p->tm_yday + 7 -
tim_p->tm_wday) / 7);
count += 2;
}
else
return 0;
break;
case 'w':
if (count < maxsize - 1)
{
sprintf (&s[count], "%1.1d",
tim_p->tm_wday);
count++;
}
else
return 0;
break;
case 'W':
if (count < maxsize - 2)
{
int wday = (tim_p->tm_wday) ? tim_p->tm_wday - 1 : 6;
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sprintf (&s[count], "%2.2d",
(tim_p->tm_yday + 7 -
wday) / 7);
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count += 2;
}
else
return 0;
break;
case 'x':
if (count < maxsize - 15)
{
for (i = 0; i < 3; i++)
s[count++] =
dname[tim_p->tm_wday][i];
s[count++] = ' ';
for (i = 0; i < 3; i++)
s[count++] =
mname[tim_p->tm_mon][i];
sprintf (&s[count],
" %.2d %.4d", tim_p->tm_mday,
1900 + tim_p->tm_year);
count += 8;
}
else
return 0;
break;
case 'X':
if (count < maxsize - 8)
{
sprintf (&s[count],
"%2.2d:%2.2d:%2.2d",
tim_p->tm_hour, tim_p->tm_min,
tim_p->tm_sec);
count += 8;
}
else
return 0;
break;
case 'y':
if (count < maxsize - 2)
{
/* The year could be greater than 100, so we need the value
modulo 100. The year could be negative, so we need to
correct for a possible negative remainder. */
sprintf (&s[count], "%2.2d",
(tim_p->tm_year % 100 + 100) % 100);
count += 2;
}
else
return 0;
break;
case 'Y':
if (count < maxsize - 4)
{
sprintf (&s[count], "%.4d",
1900 + tim_p->tm_year);
count += 4;
}
else
return 0;
break;
case 'Z':
break;
case '%':
if (count < maxsize - 1)
s[count++] = '%';
else
return 0;
break;
}
if (*format)
format++;
else
break;
}
s[count] = '\0';
return count;
}