#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <ctype.h>
const char * strp_weekdays[] =
{ "sunday", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday" };
const char * strp_monthnames[] =
{ "january", "february", "march", "april", "may", "june", "july", "august", "september", "october", "november", "december" };
bool strp_atoi(const char * & s, int & result, int low, int high, int offset)
{
bool worked = false;
char * end;
unsigned long num = strtoul(s, &end, 10);
if (num >= (unsigned long)low && num <= (unsigned long)high)
{
result = (int)(num + offset);
s = end;
worked = true;
}
return worked;
}
char * strptime(const char *s, const char *format, struct tm *tm)
{
bool working = true;
while (working && *format && *s)
{
switch (*format)
{
case '%':
{
++format;
switch (*format)
{
case 'a':
case 'A': // weekday name
tm->tm_wday = -1;
working = false;
for (int i = 0; i < 7; ++i)
{
size_t len = strlen(strp_weekdays[i]);
if (!strnicmp(strp_weekdays[i], s, len))
{
tm->tm_wday = i;
s += len;
working = true;
break;
}
else if (!strnicmp(strp_weekdays[i], s, 3))
{
tm->tm_wday = i;
s += 3;
working = true;
break;
}
}
break;
case 'b':
case 'B':
case 'h': // month name
tm->tm_mon = -1;
working = false;
for (int i = 0; i < 12; ++i)
{
size_t len = strlen(strp_monthnames[i]);
if (!strnicmp(strp_monthnames[i], s, len))
{
tm->tm_mon = i;
s += len;
working = true;
break;
}
else if (!strnicmp(strp_monthnames[i], s, 3))
{
tm->tm_mon = i;
s += 3;
working = true;
break;
}
}
break;
case 'd':
case 'e': // day of month number
working = strp_atoi(s, tm->tm_mday, 1, 31, 0);
break;
case 'D': // %m/%d/%y
{
const char * s_save = s;
working = strp_atoi(s, tm->tm_mon, 1, 12, -1);
if (working && *s == '/')
{
++s;
working = strp_atoi(s, tm->tm_mday, 1, 31, 0);
if (working && *s == '/')
{
++s;
working = strp_atoi(s, tm->tm_year, 0, 99, 0);
if (working && tm->tm_year < 69)
tm->tm_year += 100;
}
}
if (!working)
s = s_save;
}
break;
case 'H': // hour
working = strp_atoi(s, tm->tm_hour, 0, 23, 0);
break;
case 'I': // hour 12-hour clock
working = strp_atoi(s, tm->tm_hour, 1, 12, 0);
break;
case 'j': // day number of year
working = strp_atoi(s, tm->tm_yday, 1, 366, -1);
break;
case 'm': // month number
working = strp_atoi(s, tm->tm_mon, 1, 12, -1);
break;
case 'M': // minute
working = strp_atoi(s, tm->tm_min, 0, 59, 0);
break;
case 'n': // arbitrary whitespace
case 't':
while (isspace((int)*s))
++s;
break;
case 'p': // am / pm
if (!strnicmp(s, "am", 2))
{ // the hour will be 1 -> 12 maps to 12 am, 1 am .. 11 am, 12 noon 12 pm .. 11 pm
if (tm->tm_hour == 12) // 12 am == 00 hours
tm->tm_hour = 0;
}
else if (!strnicmp(s, "pm", 2))
{
if (tm->tm_hour < 12) // 12 pm == 12 hours
tm->tm_hour += 12; // 1 pm -> 13 hours, 11 pm -> 23 hours
}
else
working = false;
break;
case 'r': // 12 hour clock %I:%M:%S %p
{
const char * s_save = s;
working = strp_atoi(s, tm->tm_hour, 1, 12, 0);
if (working && *s == ':')
{
++s;
working = strp_atoi(s, tm->tm_min, 0, 59, 0);
if (working && *s == ':')
{
++s;
working = strp_atoi(s, tm->tm_sec, 0, 60, 0);
if (working && isspace((int)*s))
{
++s;
while (isspace((int)*s))
++s;
if (!strnicmp(s, "am", 2))
{ // the hour will be 1 -> 12 maps to 12 am, 1 am .. 11 am, 12 noon 12 pm .. 11 pm
if (tm->tm_hour == 12) // 12 am == 00 hours
tm->tm_hour = 0;
}
else if (!strnicmp(s, "pm", 2))
{
if (tm->tm_hour < 12) // 12 pm == 12 hours
tm->tm_hour += 12; // 1 pm -> 13 hours, 11 pm -> 23 hours
}
else
working = false;
}
}
}
if (!working)
s = s_save;
}
break;
case 'R': // %H:%M
{
const char * s_save = s;
working = strp_atoi(s, tm->tm_hour, 0, 23, 0);
if (working && *s == ':')
{
++s;
working = strp_atoi(s, tm->tm_min, 0, 59, 0);
}
if (!working)
s = s_save;
}
break;
case 'S': // seconds
working = strp_atoi(s, tm->tm_sec, 0, 60, 0);
break;
case 'T': // %H:%M:%S
{
const char * s_save = s;
working = strp_atoi(s, tm->tm_hour, 0, 23, 0);
if (working && *s == ':')
{
++s;
working = strp_atoi(s, tm->tm_min, 0, 59, 0);
if (working && *s == ':')
{
++s;
working = strp_atoi(s, tm->tm_sec, 0, 60, 0);
}
}
if (!working)
s = s_save;
}
break;
case 'w': // weekday number 0->6 sunday->saturday
working = strp_atoi(s, tm->tm_wday, 0, 6, 0);
break;
case 'Y': // year
working = strp_atoi(s, tm->tm_year, 1900, 65535, -1900);
break;
case 'y': // 2-digit year
working = strp_atoi(s, tm->tm_year, 0, 99, 0);
if (working && tm->tm_year < 69)
tm->tm_year += 100;
break;
case '%': // escaped
if (*s != '%')
working = false;
++s;
break;
default:
working = false;
}
}
break;
case ' ':
case '\t':
case '\r':
case '\n':
case '\f':
case '\v':
// zero or more whitespaces:
while (isspace((int)*s))
++s;
break;
default:
// match character
if (*s != *format)
working = false;
else
++s;
break;
}
++format;
}
return (working ? (char *)s : 0);
}