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Why isn't this working?

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helpme123456789 helpme123456789 is offline

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Why isn't this working?

Sep 13th, 2009

This is what I have so far. This isn't working and this isn't even close to working. I'm not that experienced at C++ so I was hoping that someone would help me please. The assignment is basically to write a code to validate an email address to see what characters are allowed and what characters aren't allowed. Please help in anyway possible.

Thank you.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
// reading a text file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
 
int spc_email_isvalid(const char *address) {
  int        count = 0;
  const char *c, *domain;
  static char *specialchars = "()<>@,;:\\\"[]";
 
  // validate the name portion (name@domain)
  for (c = address;  *c;  c++) {
    if (*c == '\"' &amp;&amp; (c == address || *(c - 1) == '.' || *(c - 1) ==
        '\"')) {
      while (*++c) {
        if (*c == '\"') break;
        if (*c == '\\' &amp;&amp; (*++c == ' ')) continue;
        if (*c < ' ' || *c >= 127) return 0;
      }
      if (!*c++) return 0;
      if (*c == '@') break;
      if (*c != '.') return 0;
      continue;
    }
    if (*c == '@') break;
    if (*c <= ' ' || *c >= 127) return 0;
    if (strchr(specialchars, *c)) return 0;
  }
  if (c == address || *(c - 1) == '.') return 0;
 
  // validate the domain portion (name@domain)
  if (!*(domain = ++c)) return 0;
  do {
    if (*c == '.') {
      if (c == domain || *(c - 1) == '.') return 0;
      count++;
    }
    if (*c <= ' ' || *c &>= 127) return 0;
    if (strchr(specialchars, *c)) return 0;
  } while (*++c);
 
  return (count >= 1);
}
 
*/
// reading a text file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int spc_email_isvalid(const char *address) {
  int        count = 0;
  const char *c, *domain;
  static char *specialchars = "()<>@,;:\\\"[]";

  // validate the name portion (name@domain)
  for (c = address;  *c;  c++) {
    if (*c == '\"' &amp;&amp; (c == address || *(c - 1) == '.' || *(c - 1) ==
        '\"')) {
      while (*++c) {
        if (*c == '\"') break;
        if (*c == '\\' &amp;&amp; (*++c == ' ')) continue;
        if (*c < ' ' || *c >= 127) return 0;
      }
      if (!*c++) return 0;
      if (*c == '@') break;
      if (*c != '.') return 0;
      continue;
    }
    if (*c == '@') break;
    if (*c <= ' ' || *c >= 127) return 0;
    if (strchr(specialchars, *c)) return 0;
  }
  if (c == address || *(c - 1) == '.') return 0;

  // validate the domain portion (name@domain)
  if (!*(domain = ++c)) return 0;
  do {
    if (*c == '.') {
      if (c == domain || *(c - 1) == '.') return 0;
      count++;
    }
    if (*c <= ' ' || *c &>= 127) return 0;
    if (strchr(specialchars, *c)) return 0;
  } while (*++c);

  return (count >= 1);
}

*/

Last edited by John A; Sep 14th, 2009 at 3:22 am. Reason: added code tags

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VernonDozier VernonDozier is offline

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Re: Why isn't this working?

Sep 13th, 2009

Code tags:

[code]
// paste code here
[/code]

You can use pointers and pointer arithmetic to isolate the characters in a string, but I think the code is much more readable if you use the [] operator...

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
    char* address = "joe_smith@yahoo.com";
 
    for (int i = 0; i < strlen (address); i++)
    {
        char letter = address[i];
        cout << letter;
    }
 
    for (char* c = address; *c != 0; c++)
    {
        char letter = *c;
        cout << letter;
    }
    char* address = "joe_smith@yahoo.com";
    
    for (int i = 0; i < strlen (address); i++)
    {
        char letter = address[i];
        cout << letter;
    }

    for (char* c = address; *c != 0; c++)
    {
        char letter = *c;
        cout << letter;
    }

Again, both work, but I think the first is slightly more readable than the second. As to your program, the code is a bit hard to follow. One, if this is a boolean function, since this is C++, not C, might as well take advantage of that and make use words like bool, true, and false so it's obvious that that is what you are doing.

First, decide what's legal and what isn't in an e-mail name. the explain in a few sentences in English what you are doing. I can sort of tell, but not really. What input works? What doesn't? What's breaking here? What valid e-mail address is being returned as invalid? What invalid e-mail address is being returned as valid? Post with code tags or it's really hard to read the code.

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Dave Sinkula Dave Sinkula is offline

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Re: Why isn't this working?

Sep 13th, 2009

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
for (int i = 0; i < strlen (address); i++)
for (int i = 0; i < strlen (address); i++)

Don't use strlen in a loop condition.

"One of the methods used by statists to destroy capitalism consists in establishing controls that tie a given industry hand and foot, making it unable to solve its problems, then declaring that freedom has failed and stronger controls are necessary." --Ayn Rand

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Re: Why isn't this working?

Sep 13th, 2009

•

Originally Posted by Dave Sinkula

Help with Code Tags

C++ Syntax (Toggle Plain Text)
for (int i = 0; i < strlen (address); i++)
for (int i = 0; i < strlen (address); i++)
Don't use strlen in a loop condition.

Good point. I was thinking in terms of code readability rather than efficiency, but there's no reason you can't have both. E-mails will likely be fairly short strings, but you're correct; calculations like these should happen before the loop starts since they won't change and you're just going to keep recalculating the same thing each trip through the loop.

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helpme123456789 helpme123456789 is offline

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Re: Why isn't this working?

Sep 14th, 2009

Thanks for replying. What I am trying to do is the following:

Email Address,First Name,Last Name,Custom Data

* [Email Address] Allows up to 255 characters
* [First Name] Allows up to 50 characters
* [Last Name] Allows up to 50 characters
* [Custom Value] Allows up to 255 characters

Allowed Characters:

* Letters (A-Z) and (a-z)
* Hypens (-)
* Underscores (_)
* Numbers (0-9)
* Decimal or period (.)
* Only one single apostrophe allowed (')

Characters Not Allowed:

*! “ ” # $ % & ‘ ’ ( ) * + ; , / : < > [ ] { } = ? ^ \ | ~ `

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Re: Why isn't this working?

Sep 14th, 2009

Do it one character at a time. Isolate the character, then test it. You have a whole bunch of compound statements which, while they may correct, make the code a little hard to follow, at least for me. The last name, first name, and custom value validation should have their own criteria and be in their own functions. Stick with the e-mail validation.

I'm not 100% sure what the e-mail validation rules are. Double-check them. I think you need a rule in there where you need to have exactly one @. Could be wrong.

Anyway, nail down some very exact criteria (you might have to research this), then go through character by character and test them. Any illegal character returns false. Anything that passes all tests returns true. Check the cctype library. It has some good character testing functions like isalnum , which could come in handy. you may want to repost the code, as it got a little garbled (i.e. "&amp").

Last edited by VernonDozier; Sep 14th, 2009 at 1:48 pm.

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Re: Why isn't this working?

Sep 14th, 2009

Functions like strcspn or strspn might also come in handy.

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Re: Why isn't this working?

Sep 14th, 2009

•

Originally Posted by Dave Sinkula

Help with Code Tags

C++ Syntax (Toggle Plain Text)
for (int i = 0; i < strlen (address); i++)
for (int i = 0; i < strlen (address); i++)
Don't use strlen in a loop condition.

I thought most compiler would optimize it. I'll check to see
if it does with Visual Studio Express 2008.

Help with Code Tags

(Toggle Plain Text)

1) Prove that the area of a circle is pi*r^2, where "r" is the radius of the circle.
2) Problem 2[b]solved by : jonsca

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Re: Why isn't this working?

Sep 14th, 2009

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Originally Posted by firstPerson

I thought most compiler would optimize it. I'll check to see
if it does with Visual Studio Express 2008.

Contained in the link I posted was another link to a discussion thread that mentions some things that would make this "assumed optimization" questionable (for the particular case being discussed). Perhaps that can shed further light on this for you.