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用asp判断email地址是否有效
2000-03-23· 王俊·cpcw

　　在用asp编写页面时，如果涉及到邮件发送，一般会要求输入email地址。错误的email地址往往带来许多不必要的麻烦，用下面的函数isvalidemail就能判断出一个email地址是否有效。
函数源代码：
<%
function isvalidemail(email)
validflag = false
if (email <> "") and (instr(1, email, "@") > 0) and (instr(1, email, ".") > 0) then
atcount = 0
specialflag = false
for atloop = 1 to len(email)
atchr = mid(email, atloop, 1)
if atchr = "@" then atcount = atcount + 1
if (atchr >= chr(32)) and (atchr <= chr(44)) then specialflag = true
if (atchr = chr(47)) or (atchr = chr(96)) or (atchr >= chr(123)) then specialflag = true
if (atchr >= chr(58)) and (atchr <= chr(63)) then specialflag = true
if (atchr >= chr(91)) and (atchr <= chr(94)) then specialflag = true
next
if (atcount = 1) and (specialflag = false) then
badflag = false
tary1 = split(email, "@")
username = tary1(0)
domainname = tary1(1)
if (username = "") or (domainname = "") then badflag = true
if mid(domainname, 1, 1) = "." then badflag = true
if mid(domainname, len(domainname), 1) = "." then badflag = true
validflag = true
end if
end if
if badflag = true then validflag = false
isvalidemail = validflag
end function
%>
用法举例：
isvalidemail("my_263_email@263.net") 返回ture
isvalidemail("zh99wj@tonghua.com.cn") 返回ture
isvalidemail("myemail263.net") 返回false
isvalidemail("my_263_email@263) 返回false
请注意，函数只是判断email地址格式是否有效，但并不能检查该地址是否确实存在。

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