var code; //在全局 定义验证码    
function createCode(a) {
	code = "";
	var codeLength = 4;//验证码的长度 
	var checkCode = document.getElementById(a);
	var selectChar = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9);//所有候选组成验证码的字符，当然也可以用中文的   
	for (var i = 0; i < codeLength; i++) {
		var charIndex = Math.floor(Math.random() * 10);
		code += selectChar[charIndex];
	}

							 //       alert(code);     
	if (checkCode) {
		checkCode.className = "code";
		checkCode.value = code;
	}
}
function validate(a,b,num) {
	var inputCode = document.getElementById(a).value;
	var validateCode = document.getElementById(b).value;
	if (inputCode.length <= 0) {
		alert("\u8bf7\u8f93\u5165\u9a8c\u8bc1\u7801\uff01");
	} else {
		if (inputCode != validateCode) {
			alert("\u9a8c\u8bc1\u7801\u8f93\u5165\u9519\u8bef\uff01");
			createCode(b);//刷新验证码   
		} else {
			document.forms[num].submit();
		}
	}
}
function confrm(a,b,num) {
	if (event.keyCode == 13) {
		validate(a,b,num);

      				//alert('按回车了');   
	}
}