<script language="javascript" type="text/javascript">
function AREA_MEASURES()
{
	this.mSquare_kilometer = (1000 * 1000)
	this.mHectare = (100 * 100)
	this.mSquare_meter = 1
	this.mAre = ((10000/15) * this.mSquare_meter)
	this.mSquare_decimeter = (0.1 * 0.1)
	this.mSquare_centimeter = (0.01 * 0.01)
	this.mSquare_millimeter = (0.001 * 0.001)
	this.engSquare_foot = (0.3048 * 0.3048)
	this.engSquare_yard = (3 * 3 * this.engSquare_foot)
	this.usSquare_rod = (16.5 *16.5 * this.engSquare_foot)
	this.engAcre = 160 * this.usSquare_rod
	this.engSquare_mile = (5280 *5280 * this.engSquare_foot)
	this.engSquare_inch = (this.engSquare_foot / (12 * 12))
}
var area_data = new AREA_MEASURES();
function checkNum(str) {
	for (var i=0; i<str.length; i++) {
		var ch = str.substring(i, i + 1)
		if (ch!="." && ch!="+" && ch!="-" && ch!="e" && ch!="E" && (ch < "0" || ch > "9")) {
			alert("请输入有效的数字");
			return false;
		}
	}
	return true
}
function normalize(what,digits) {
	var str=""+what;
	var pp=Math.max(str.lastIndexOf("+"),str.lastIndexOf("-"));
	var idot=str.indexOf(".");
	if (idot>=1) {
		var ee=(pp>0)?str.substring(pp-1,str.length):"";
		digits+=idot;
		if (digits>=str.length)
			return str;
				if (pp>0 && digits>=pp)
			digits-=pp;
		var c=eval(str.charAt(digits));
		var ipos=digits-1;
		if (c>=5)  {
			while (str.charAt(ipos)=="9")
				ipos--;
			if (str.charAt(ipos)==".") {
				var nc=eval(str.substring(0,idot))+1;
				if (nc==10 && ee.length>0) {
					nc=1;
					ee="e"+(eval(ee.substring(1,ee.length))+1);
				}
				return ""+nc+ee;
			}
			return str.substring(0,ipos)+(eval(str.charAt(ipos))+1)+ee;
		} else
			var ret=str.substring(0,digits)+ee;
		for (var i=0; i<ret.length; i++)
				if (ret.charAt(i)>"0" && ret.charAt(i)<="9")
					return ret;
		return str;
	}
	return str;
}
function compute(obj,val,data) {
	if (obj[val].value) {
		var uval=0;
		uval = obj[val].value*data[val];
		if( (uval >= 0) && (obj[val].value.indexOf("-") != -1) ) {
			uval = -uval;    // *** Hack for Opera 4.0  2000-10-14
		}
		for (var i in data)
			obj[i].value=normalize(uval/data[i],8);
	}
}
function resetValues(form,data) {
		for (var i in data)
			form[i].value="";
}

function resetAll(form) {
	resetValues(form,area_data);
}
</script>

<table width="670" borderColorDark="#ffffff" borderColorLight="#008000" border="1" cellpadding="3" cellspacing="0" align="center">
	<form action="">
	<tr height=10><td colspan=4 bgcolor="#CCE6CD" align="center">面积转换换算器 &nbsp; <a href="javascript:window.external.addfavorite('http://www.famens.com', '面积转换换算器')">←【加入收藏夹】</a></td></tr>
	<tr>
		<td align=right nowrap>平方公里<font style="font-size=9px;">(km<sup>2</sup>)</font></td>
		<td align=left><input name=mSquare_kilometer size="15"> <input onClick="if (checkNum(mSquare_kilometer.value)) compute(this.form,mSquare_kilometer.name,area_data)" type=button value="换算" name=mSquare_kilometer_bt></td>
		<td align=right nowrap>公顷<font style="font-size=9px;">(ha)</font></td>
		<td align=left><input name=mHectare size="15"> <input onClick="if (checkNum(mHectare.value)) compute(this.form,mHectare.name,area_data)" type=button value="换算" name=mHectare_bt></td>
	</tr>
	<tr>
		<td align=right nowrap>市亩</td>
		<td align=left><input name=mAre size="15"> <input onClick="if (checkNum(mAre.value)) compute(this.form,mAre.name,area_data)" type=button value="换算" name=mAre_bt></td>
		<td align=right nowrap>平方米<font style="font-size=9px;">(m<sup>2</sup>)</font></td>
		<td align=left><input name=mSquare_meter size="15"> <input onClick="if (checkNum(mSquare_meter.value)) compute(this.form,mSquare_meter.name,area_data)" type=button value="换算" name=mSquare_meter_bt></td>
	</tr>
	<tr>
		<td align=right nowrap>平方分米<font style="font-size=9px;">(dm<sup>2</sup>)</font></td>
		<td align=left><input name=mSquare_decimeter size="15"> <input onClick="if (checkNum(mSquare_decimeter.value)) compute(this.form,mSquare_decimeter.name,area_data)" type=button value="换算" name=mSquare_decimeter_bt></td>
		<td align=right nowrap>平方厘米<font style="font-size=9px;">(cm<sup>2</sup>)</font></td>
		<td align=left><input name=mSquare_centimeter size="15"> <input onClick="if (checkNum(mSquare_centimeter.value)) compute(this.form,mSquare_centimeter.name,area_data)" type=button value="换算" name=mSquare_centimeter_bt></td>
	</tr>
	<tr>
		<td align=right nowrap>平方毫米<font style="font-size=9px;">(mm<sup>2</sup>)</font></td>
		<td align=left><input name=mSquare_millimeter size="15"> <input onClick="if (checkNum(mSquare_millimeter.value)) compute(this.form,mSquare_millimeter.name,area_data)" type=button value="换算" name=mSquare_millimeter_bt></td>
		<td align=right nowrap>平方英里<font style="font-size=9px;">(sq mi)</font></td>
		<td align=left><input name=engSquare_mile size="15"> <input onClick="if (checkNum(engSquare_mile.value)) compute(this.form,engSquare_mile.name,area_data)" type=button value="换算" name=engSquare_mile_bt></td>
	</tr>
	<tr>
		<td align=right nowrap>英亩</td>
		<td align=left><input name=engAcre size="15"> <input onClick="if (checkNum(engAcre.value)) compute(this.form,engAcre.name,area_data)" type=button value="换算" name=engAcre_bt></td>
		<td align=right nowrap>平方竿<font style="font-size=9px;">(sq rd)</font></td>
		<td align=left><input name=usSquare_rod size="15"> <input onClick="if (checkNum(usSquare_rod.value)) compute(this.form,usSquare_rod.name,area_data)" type=button value="换算" name=usSquare_rod_bt></td>
	</tr>
	<tr>
		<td align=right nowrap>平方码<font style="font-size=9px;">(sq yd)</font></td>
		<td align=left><input name=engSquare_yard size="15"> <input onClick="if (checkNum(engSquare_yard.value)) compute(this.form,engSquare_yard.name,area_data)" type=button value="换算" name=engSquare_yard_bt></td>
		<td align=right nowrap>平方英尺<font style="font-size=9px;">(sq ft)</font></td>
		<td align=left><input name=engSquare_foot size="15"> <input onClick="if (checkNum(engSquare_foot.value)) compute(this.form,engSquare_foot.name,area_data)" type=button value="换算" name=engSquare_foot_bt></td>
	</tr>
	<tr>
		<td align=right nowrap>平方英寸<font style="font-size=9px;">(sq in)</font></td>
		<td align=left><input name=engSquare_inch size="15"> <input onClick="if (checkNum(engSquare_inch.value)) compute(this.form,engSquare_inch.name,area_data)" type=button value="换算" name=engSquare_inch_bt></td>
		<td colspan=2><div align="right"><input onClick=resetAll(this.form) type=button value="数据重置" name=res7></div></td>
	</tr>
</table>