Geografic-Information-System/lib/datetime/sign.c

/*
 * Copyright (C) 1995.  Bill Brown <brown@gis.uiuc.edu> & Michael Shapiro
 *
 * This program is free software under the GPL (>=v2)
 * Read the file GPL.TXT coming with GRASS for details.
 */
#include <grass/datetime.h>


/*!
 * \brief 
 *
 * Returns:  
 * 1 if the Datetime is positive  
 * 0 otherwise
 *
 *  \param dt
 *  \return int
 */

int datetime_is_positive(const DateTime * dt)
{
    return dt->positive != 0;
}

/*!
 * \brief 
 *
 * Returns:  
 * 1 if the DateTime is negative
 * 0 otherwise
 *
 *  \param dt
 *  \return int
 */

int datetime_is_negative(const DateTime * dt)
{
    return dt->positive == 0;
}


/*!
 * \brief 
 *
 * Makes the DateTime positive. (A.D. for ABSOLUTE DateTimes)
 *
 *  \param dt
 *  \return void
 */

void datetime_set_positive(DateTime * dt)
{
    dt->positive = 1;
}


/*!
 * \brief 
 *
 * Makes the DateTime negative. (B.C. for ABSOLUTE DateTimes)
 *
 *  \param dt
 *  \return void
 */

void datetime_set_negative(DateTime * dt)
{
    dt->positive = 0;
}


/*!
 * \brief 
 *
 *  \param dt
 *  \return void
 */

void datetime_invert_sign(DateTime * dt)
{
    dt->positive = !dt->positive;
}