Regex - Only allow a-zAZ0-9 in e-mail address validation

Hello,

I am running a program that makes the registration of users with their e-mail address. It makes the registration using mysql.

The problem is that when someone types the e-mail address with special characters, such as {, ƒ and so on, the program gets killed, returning syntax error in mysql.

I was wondering if someone could help me fixing the code.

I tried several ways, but could not make it.

Here is the code:

Code:

int validate_email(const char *email)
{
if (strchr(email, '\\'))
return 0;
else if (strchr(email, '\"'))
return 0;
else if (strchr(email, '\''))
return 0;
else if (strchr(email, '@') && strchr(email, '.'))
return 1;
else
return 0;
} 

With this code I can filter \, ' and ", but not other special chars.

Thank you!!

 

Code:

#include <ctype.h>
#include <string.h>

int validate_email(char* mailaddr)
{
      /* allow alpha, digits, @ and underscore - you can modify this to 
          include other permissible characters */
      int i, reply = 1, c;
      
      for( i = 0; i < strlen(mailaddr) && reply; i++ )
      {
            c = mailaddr[ i ];
            if( ! isalpha(c) && ! isdigit(c) && c != '@' && c != '_' )
                  reply = 0;
      }

      return reply;
}