var code ;  
function createCode()  
{   
	code = "";  
	var codeLength = 4; 
	var checkCode = document.getElementById("checkCode");
	var validate_code_two = document.getElementById("verification"); 
	var company = document.getElementById("company");
	var selectChar = new Array(0,1,2,3,4,5,6,7,8,9,'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');// 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()*36);  
		code +=selectChar[charIndex];  		
	}  
	if(checkCode)  
	{  
		checkCode.className="code";  
		validate_code_two.value = code + company.value;
		checkCode.innerHTML = "<center>" + code + "</center>";  
	}  
}  

function validate_code()  
{  
	var inputCode = document.getElementById("validate_code").value;  
	if(inputCode.length <=0)  
	{  
		alert("Please enter validate code!"); 
		return false; 
	}  
	if(inputCode != code )  
	{  
		alert("Validate code is wrong. Please enter again!");  
		createCode(); 
		return false;
	}             
}