function roll() {
	var preload = new Array();
	var imgs = document.getElementsByTagName('img');
	var total = imgs.length;
	for (i=0; i<total; i++) {
		if (imgs[i].className == 'rov') {
			var out = imgs[i].getAttribute('src');
			var last = out.length;
			var type = out.substring(out.lastIndexOf('.'), last);
			var over = out.replace(type, 'o'+type);
			//preload
			preload[i] = document.createElement("img");
			preload[i].src = over;
			//over
			imgs[i].setAttribute('over', over);
			imgs[i].onmouseover = imgs[i].onmousedown = function () {
				this.src = this.getAttribute('over');
			};
			//out
			imgs[i].setAttribute('out', out);
			imgs[i].onmouseout = imgs[i].onmouseup = function () {
				this.src = this.getAttribute('out');
			};
		}
	}
}
if (window.addEventListener) {
	window.addEventListener("load", roll, false);
} else if (window.attachEvent) {
	window.attachEvent("onload", roll);
}
function tabSwitch(ctID) {
	var count = 0;
	var tab = document.getElementById('tabBlockList');
	var tabs = tab.getElementsByTagName('li');
	var total = tabs.length;
	var targetTab = 'tab_'+ctID;
	for (i=0; i<total; i++) {
		count++;
		var targetID = 'list_'+count;
		var targetList = document.getElementById(targetID);
		var targetState = tabs[i].firstChild;
		if (tabs[i].getAttribute('name') == targetTab) {
			targetState.className = 'stay';
			targetList.className = 'open';
		} else {
			targetState.className = 'act';
			targetList.className = 'close';
		}
	}
}
function dispAnswer() {
	var ans = document.getElementsByTagName('table');
	var total = ans.length;
	var img = document.getElementById('answer');
	for (i=0; i<total; i++) {
		if (ans[i].className == 'close') {
			ans[i].className = 'open';
			img.setAttribute('src', '../../../img/ind_img_close.jpg');
			img.setAttribute('alt', '解答を閉じる');
		} else if (ans[i].className == 'open') {
			ans[i].className = 'close';
			img.setAttribute('src', '../../../img/ind_img_open.jpg');
			img.setAttribute('alt', '解答を表示する');
		}
	}
}