/* * (C)2012 Michael Duane Rice All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. Redistributions in binary * form must reproduce the above copyright notice, this list of conditions * and the following disclaimer in the documentation and/or other materials * provided with the distribution. Neither the name of the copyright holders * nor the names of contributors may be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* $Id$ */ /* Return the week of year, where 'base' represents the first day of the week. In the USA, the week is generally considered to start on Sunday (base = 0), while in Europe it is generally considered to be Monday (base = 1). Return value ranges from 0 to 52. */ #include <time.h> uint8_t week_of_year(const struct tm * timestruct, uint8_t base) { int first, n; /* find the first base day of the year (start of week 1) */ first = 7 + timestruct->tm_yday - timestruct->tm_wday + base; first %= 7; /* find days since that first base day*/ n = timestruct->tm_yday - first; /* if negative, we are in week 0 */ if (n < 0) return 0; return n / 7 + 1; }