验证字符串是否是有效的电子邮件地址的最优雅的代码是什么?
当前回答
我写了一个函数来检查电子邮件是否有效。在大多数情况下,这似乎对我很有效。
结果:
dasddas-@.com => FALSE
-asd@das.com => FALSE
as3d@dac.coas- => FALSE
dsq!a?@das.com => FALSE
_dasd@sd.com => FALSE
dad@sds => FALSE
asd-@asd.com => FALSE
dasd_-@jdas.com => FALSE
asd@dasd@asd.cm => FALSE
da23@das..com => FALSE
_dasd_das_@9.com => FALSE
d23d@da9.co9 => TRUE
dasd.dadas@dasd.com => TRUE
dda_das@das-dasd.com => TRUE
dasd-dasd@das.com.das => TRUE
代码:
private bool IsValidEmail(string email)
{
bool valid = false;
try
{
var addr = new System.Net.Mail.MailAddress(email);
valid = true;
}
catch
{
valid = false;
goto End_Func;
}
valid = false;
int pos_at = email.IndexOf('@');
char checker = Convert.ToChar(email.Substring(pos_at + 1, 1));
var chars = "qwertyuiopasdfghjklzxcvbnm0123456789";
foreach (char chr in chars)
{
if (checker == chr)
{
valid = true;
break;
}
}
if (valid == false)
{
goto End_Func;
}
int pos_dot = email.IndexOf('.', pos_at + 1);
if(pos_dot == -1)
{
valid = false;
goto End_Func;
}
valid = false;
try
{
checker = Convert.ToChar(email.Substring(pos_dot + 1, 1));
foreach (char chr in chars)
{
if (checker == chr)
{
valid = true;
break;
}
}
}
catch
{
valid = false;
goto End_Func;
}
Regex valid_checker = new Regex(@"^[a-zA-Z0-9_@.-]*$");
valid = valid_checker.IsMatch(email);
if (valid == false)
{
goto End_Func;
}
List<int> pos_list = new List<int> { };
int pos = 0;
while (email.IndexOf('_', pos) != -1)
{
pos_list.Add(email.IndexOf('_', pos));
pos = email.IndexOf('_', pos) + 1;
}
pos = 0;
while (email.IndexOf('.', pos) != -1)
{
pos_list.Add(email.IndexOf('.', pos));
pos = email.IndexOf('.', pos) + 1;
}
pos = 0;
while (email.IndexOf('-', pos) != -1)
{
pos_list.Add(email.IndexOf('-', pos));
pos = email.IndexOf('-', pos) + 1;
}
int sp_cnt = pos_list.Count();
pos_list.Sort();
for (int i = 0; i < sp_cnt - 1; i++)
{
if (pos_list[i] + 1 == pos_list[i + 1])
{
valid = false;
break;
}
if (pos_list[i]+1 == pos_at || pos_list[i]+1 == pos_dot)
{
valid = false;
break;
}
}
if(valid == false)
{
goto End_Func;
}
if (pos_list[sp_cnt - 1] == email.Length - 1 || pos_list[0] == 0)
{
valid = false;
}
End_Func:;
return valid;
}
其他回答
电子邮件地址验证并不像看起来那么简单。实际上,从理论上讲,仅使用正则表达式完全验证电子邮件地址是不可能的。
请查看我的博客文章,了解关于这个主题的讨论以及使用FParsec的f#实现。[/ shameless_plug]
.net 4.5增加了System.ComponentModel.DataAnnotations.EmailAddressAttribute
你可以浏览EmailAddressAttribute的源代码,这是它内部使用的正则表达式:
const string pattern = @"^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$";
/// <summary>
/// Validates the email if it follows the valid email format
/// </summary>
/// <param name="emailAddress"></param>
/// <returns></returns>
public static bool EmailIsValid(string emailAddress)
{
//if string is not null and empty then check for email follow the format
return string.IsNullOrEmpty(emailAddress)?false : new Regex(@"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$", RegexOptions.IgnoreCase).IsMatch(emailAddress);
}
通过system . text . regulareexpressions检查电子邮件字符串的格式是否正确:
public static bool IsValidEmailId(string InputEmail)
{
Regex regex = new Regex(@"^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$");
Match match = regex.Match(InputEmail);
if (match.Success)
return true;
else
return false;
}
protected void Email_TextChanged(object sender, EventArgs e)
{
String UserEmail = Email.Text;
if (IsValidEmailId(UserEmail))
{
Label4.Text = "This email is correct formate";
}
else
{
Label4.Text = "This email isn't correct formate";
}
}
我发现这个正则表达式在检查@标记以外的东西和接受奇怪的边缘情况之间是一个很好的权衡:
^[^@\s]+@[^@\s]+(\.[^@\s]+)+$
它至少会让你在@标记周围放一些东西,并且至少放一个正常的域。
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