Problem - Kevin Tafuro

if (*c != '%' || !isxdigit(c[1]) || !isxdigit(c[2])) *ptr++ = *c;
else {
*ptr++ = (SPC_BASE16_TO_10(c[1]) * 16) + (SPC_BASE16_TO_10(c[2]));
c += 2;
}
}
*ptr = 0;
if (nbytes) *nbytes = (ptr - out); /* does not include null byte */
return out;
}
See Also
• RFC 1738: Uniform Resource Locators (URL)
• Recipe 3.4
3.9 Validating Email Addresses
Problem
Your program accepts an email address as input, and you need to verify that the supplied
address is valid.
Solution
Scan the email address supplied by the user, and validate it against the lexical rules
set forth in RFC 822.
Discussion
RFC 822 defines the syntax for email addresses. Unfortunately, the syntax is complex,
and it supports several address formats that are no longer relevant. The fortunate
thing is that if anyone attempts to use one of these no-longer-relevant address
formats, you can be reasonably certain they are attempting to do something they are
not supposed to do.
You can use the following spc_email_isvalid( ) function to check the format of an
email address. It will perform only a syntactical check and will not actually attempt
to verify the authenticity of the address by attempting to deliver mail to it or by performing
any DNS lookups on the domain name portion of the address.
The function only validates the actual email address and will not accept any associated
data. For example, it will fail to validate “Bob Bobson ”,
but it will successfully validate “bob@bobson.com”. If the supplied email address is
syntactically valid, spc_email_isvalid( ) will return 1; otherwise, it will return 0.
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