PHP中几个常用的日期及时间格式转换及比较函数

显示日期：echo date( "Y-m-d", time() );
显示时间：echo date( "H:i:s", time() );
格式化用法，如：format_date(date( "Y-m-d", time() ))

function format_date( $STRING1 )
{
    $STRING1 = str_replace( "-0", "-", $STRING1 );
    $STR = strtok( $STRING1, "-" );
    $STRING2 = $STR."年";
    $STR = strtok( "-" );
    $STRING2 .= $STR."月";
    $STR = strtok( " " );
    $STRING2 .= $STR."日";
    return $STRING2;
}

function format_date_short1( $STRING1 )
{
    $STRING1 = str_replace( "-0", "-", $STRING1 );
    $STR = strtok( $STRING1, "-" );
    $STRING2 = $STR."年";
    $STR = strtok( "-" );
    $STRING2 .= $STR."月";
    return $STRING2;
}

function format_date_short2( $STRING1 )
{
    $STRING1 = str_replace( "-0", "-", $STRING1 );
    $STR = strtok( $STRING1, "-" );

    $STR = strtok( "-" );
    $STRING2 .= $STR."月";
    $STR = strtok( " " );
    $STRING2 .= $STR."日";
    return $STRING2;
}

function get_week( $STRING1 )
{
    $STR = strtok( $STRING1, "-" );
    $YEAR = $STR;
    $STR = strtok( "-" );
    $MONTH = $STR;
    $STR = strtok( " " );
    $DAY = $STR;
    $TIME1 = mktime( 0, 0, 0, $MONTH, $DAY, $YEAR );
    switch ( date( "w", $TIME1 ) )
    {
    case 0 :
        return "日";
    case 1 :
        return "一";
    case 2 :
        return "二";
    case 3 :
        return "三";
    case 4 :
        return "四";
    case 5 :
        return "五";