I am pretty much new with regular expression. I am developing a project in PHP and i need to validate email address. After searching in this site and google i found the following regular expression says it should work best.
if (preg_match("/^(?!(?:(?:x22?x5C[x00-x7E]x22?)|(?:x22?[^x5Cx22]x22?)){255,})(?!(?:(?:x22?x5C[x00-x7E]x22?)|(?:x22?[^x5Cx22]x22?)){65,}@)(?:(?:[x21x23-x27x2Ax2Bx2Dx2F-x39x3Dx3Fx5E-x7E]+)|(?:x22(?:[x01-x08x0Bx0Cx0E-x1Fx21x23-x5Bx5D-x7F]|(?:x5C[x00-x7F]))*x22))(?:.(?:(?:[x21x23-x27x2Ax2Bx2Dx2F-x39x3Dx3Fx5E-x7E]+)|(?:x22(?:[x01-x08x0Bx0Cx0E-x1Fx21x23-x5Bx5D-x7F]|(?:x5C[x00-x7F]))*x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))]))$/iD", strtolower($mail_address))) {
echo "valid email";
}
But when I use it I get error says,
"Warning: preg_match(): No ending delimiter '/' found"
What is wrong with this code?
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Answer
Use this instead of a regular expression:
if(filter_var($email, FILTER_VALIDATE_EMAIL)) {
//Valid email!
}
Using regular expressions to validate email addresses is not recommended as it is certainly not pretty, especially if you don’t want to exclude somebody who has a valid email address that is correct according to RFC 822 grammar.
http://www.php.net/filter_var is your best bet.
A crazy example of a regex that attempts to validate email addresses according to RFC 822 grammar:
(?:(?:rn)?[ t])*(?:(?:(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t] )+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?: rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:( ?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00- 31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)* ](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+ (?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?: (?:rn)?[ t])*))*|(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z |(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn) ?[ t])*)*<(?:(?:rn)?[ t])*(?:@(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?: rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn) ?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t] )*))*(?:,@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])* )(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t] )+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*) *:(?:(?:rn)?[ t])*)?(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+ |Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:r n)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?: rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t ]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31 ]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*]( ?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(? :(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(? :rn)?[ t])*))*>(?:(?:rn)?[ t])*)|(?:[^()<>@,;:\".[] 00-31]+(?:(? :(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)? [ t]))*"(?:(?:rn)?[ t])*)*:(?:(?:rn)?[ t])*(?:(?:(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]| \.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<> @,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|" (?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t] )*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\ ".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(? :[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[ ]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*|(?:[^()<>@,;:\".[] 00- 31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|( ?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)*<(?:(?:rn)?[ t])*(?:@(?:[^()<>@,; :\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([ ^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\" .[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[ ]r\]|\.)*](?:(?:rn)?[ t])*))*(?:,@(?:(?:rn)?[ t])*(?:[^()<>@,;:\". [] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[] r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\] |\.)*](?:(?:rn)?[ t])*))*)*:(?:(?:rn)?[ t])*)?(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\ .|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@, ;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(? :[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])* (?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\". []]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[ ^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[] ]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*>(?:(?:rn)?[ t])*)(?:,s*( ?:(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\ ".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:( ?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[ ["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t ])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t ])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(? :.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+| Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*|(?: [^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[ ]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)*<(?:(?:rn) ?[ t])*(?:@(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[[" ()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn) ?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<> @,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*(?:,@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@, ;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t] )*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\ ".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*)*:(?:(?:rn)?[ t])*)? (?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\". []]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:(?: rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[[ "()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t]) *))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t]) +|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?: .(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z |(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*>(?:( ?:rn)?[ t])*))*)?;s*)