User entered URL validation

Could anyone help me out with some validation code to remove all invalid characters from a string? I was hoping to find a way of using CString.Remove by specifying a range of ASCII numbers to remove. For instance, remove all ASCII chars with code less than 48. Obviously I could go through and say

strURL.Remove(‘ ‘);

and so on but that’s not very efficient and a lot more work! Any help much appreciated!

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Why don't you use 'InternetCanonicalizeUrl()' and check the result for 'ERROR_INTERNET_INVALID_URL'?

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wjdashwoodAuthor Commented:
Never even heard of that before. Excellent! I'll investigate further.

Roshan DavisCommented:
Thatz a nice one!

You can try this also..



    LPBC pBC,
    DWORD dwReserved


        It should be set to NULL.
        Address of a string value that contains the full URL to be checked.

        Reserved. Must be set to zero.

Return Value

Returns one of the following values:

S_OK The szURL parameter contains a valid URL.
S_FALSE The szURL parameter does not contain a valid URL.
E_INVALIDARG One of the parameters is invalid.

Function Information

Header Urlmon.h
Import library Urlmon.lib
Minimum availability Internet Explorer 3.0
Minimum operating systems Windows NT 4.0, Windows 95

Rosh :)
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Roshan DavisCommented:
Ooops, the above function is only for validating the URL
wjdashwoodAuthor Commented:
I'm trying to get InternetCanonicalizeUrl() to work but GetLastError simply returns ERROR_INVALID_PARAMETER. Can someone help me with the useage?

>>ERROR_INVALID_PARAMETER. Can someone help me with the useage?

How *are* you using it?
wjdashwoodAuthor Commented:
LPDWORD lpdwBufferLength = NULL;
LPTSTR lpszBuffer = NULL;
LPCTSTR lpszUrl = _T("");


DWORD dwLastError = GetLastError();

I guess I'm not delcaring or passing lpszBuffer and lpdwBufferLength correctly.
>>LPDWORD lpdwBufferLength = NULL;
>>LPTSTR lpszBuffer = NULL;

That actually is the problem - the API expects a buffer to receive the output, not a NULL pointer. And, what's worese, the buffer size parameter is a null pointer also.

Make it read

LPCTSTR lpszUrl = _T("");
DWORD dwBufferLength = 2 * _tcslen ( lpszUrl); // worst case
TCHAR szBuffer [ dwBufferLength];


wjdashwoodAuthor Commented:
Many thanks. I'll give that a try.
wjdashwoodAuthor Commented:
I've got it working (I had to declare a size of the szBuffer) but the function doesn't seem to remove invalid characters. Is there a flag I need to set or something?
>>but the function doesn't seem to remove invalid characters

Hm, it should *test* for them (at least this was my intention) - removing chars is a bit dangerous, as in approx. 90% of all cases you won't end up with an existing URL
wjdashwoodAuthor Commented:
Well your algorithm in the other question does exactly what I want and probably much faster :)
Well, we have a proverb here about 'catching two flies with a single slap' :o)
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