//指定した3つの数字が日付として正確か？
function _CHECK_DATE(y, m, d){
	dt = new Date(y, m - 1, d);	//変数「m」は0〜11
	
	var tg_y = dt.getYear();
	var tg_m = dt.getMonth() + 1;
	var tg_d = dt.getDate();
	
	if (tg_y < 2000) { tg_y += 1900; }
	
	if(tg_y == y && tg_m == m && tg_d == d){
		return true;
	}
	return false;
}


function _GET_STR_DATE(){
	var dt = new Date();
	var yy = dt.getYear();
	var mm = dt.getMonth() + 1;
	var dd = dt.getDate();
	if (yy < 2000) { yy += 1900; }
	if (mm < 10) { mm = "0" + mm; }
	if (dd < 10) { dd = "0" + dd; }
	
	yy = yy + "";
	mm = mm + "";
	dd = dd + "";
	
//	return yy.substr(2) + mm + dd;
	return yy + "_" + mm + "_" + dd;
}



//曜日を返す
//日曜:0 土曜:6
function _GET_WEEKVALUE(y, m, d){
	m--;
	dt = new Date(y, m, d);
	retval = dt.getDay();
	
	if(retval == 0){
		retval = "Sun";
	}else if(retval == 1){
		retval = "Mon";
	}else if(retval == 2){
		retval = "Tue";
	}else if(retval == 3){
		retval = "Wed";
	}else if(retval == 4){
		retval = "Thu";
	}else if(retval == 5){
		retval = "Fri";
	}else if(retval == 6){
		retval = "Sat";
	}
	return retval;
}


//先月を返す（yyyy_mmの形式で）
function _GET_LAST_MONTH(yyyy, mm){
	if(mm == 1){
		yyyy--;
		mm = "12";
	}else{
		mm--;
		if(mm < 10){
			mm = "0" + mm;
		}
	}
	return yyyy + "_" + mm
}


//翌月を返す（yyyy_mmの形式で）
function _GET_NEXT_MONTH(yyyy, mm){
	if(mm == 12){
		yyyy++;
		mm = "01";
	}else{
		mm++;
		if(mm < 10){
			mm = "0" + mm;
		}
	}
	return yyyy + "_" + mm
}

//指定月の日数を返す
function _GET_MONTH_DAYS(yyyy, mm){
	var str_next = _GET_NEXT_MONTH(yyyy, mm);
	var year_nex = str_next.substr(0, 4);
	var month_nex = str_next.substr(5);
	
	alert(year_nex + "\n" + month_nex);
	
	var dt_nex = new Date(Number(year_nex), Number(month_nex) - 1, 1);
	var sec_nex = dt_nex.getTime();
	
	var dt = new Date(sec_nex - (3600 * 1000 * 24));
	return dt.getDate();
}