C / C++ / MFC

Christian Graus23-Dec-02 14:21

Christian Graus

23-Dec-02 14:21

Because it's good advice ? Smile | :)

Christian

No offense, but I don't really want to encourage the creation of another VB developer.
- Larry Antram 22 Oct 2002

C# will attract all comers, where VB is for IT Journalists and managers - Michael
P Butler 05-12-2002

Again, you can screw up a C/C++ program just as easily as a VB program. OK, maybe not
as easily, but it's certainly doable. - Jamie Nordmeyer - 15-Nov-2002

C^hris L^osinger23-Dec-02 12:42

C^hris L^osinger

23-Dec-02 12:42

i've always had to write my own. luckily, you can just grab the source for MS's own strstr and tweak it. (strstr itself is like 20 lines of C)

-c

I'm not the droid you're looking for.

ThumbNailer

Nish Nishant23-Dec-02 14:12

23-Dec-02 14:12

Yup, thats what I am doing now Smile | :)

nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Victor Boctor23-Dec-02 12:52

Victor Boctor

23-Dec-02 12:52

Nishant S wrote:
Is there a case in-sensitive version of the CRT function strstr?

Unfortunately not, I always wondered why there is no strstri() or stristr() same like stricmp() Frown | :(

Possibly a good idea for a simple article. The aim is to have an optimised stristr().

Regards,
Victor

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Scott H. Settlemier23-Dec-02 15:04

Scott H. Settlemier

23-Dec-02 15:04

I guess that would be a Boyer-Moore[^] implementation
using a character test something like:

const int uc='a'-'A';
bool bMatch=c==d || c+uc==d && c>='A' && c<='Z' || c==d+uc && d>='A' && d<='Z';

Rick York23-Dec-02 13:22

Rick York

23-Dec-02 13:22

Have you looked at this ? : http://www.codeproject.com/string/stringsearch.asp

The Ten Commandments For C Programmers

Nish Nishant23-Dec-02 14:14

23-Dec-02 14:14

Cool article. But I just made my own version based on the existing one that comes with VC++.

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Anders Molin23-Dec-02 13:59

Anders Molin

23-Dec-02 13:59

Something I wrote a loooong time ago...

//case insensitive search functions...
#ifdef UNICODE
#define _tcsustr wcsustr
#else
#define _tcsustr strustr
#endif
char* strustr(char *source, char *s);
wchar_t* wcsustr(wchar_t *source, wchar_t *s);

char* strustr(char *source, char *s)
{
	//make an uppercase copy af source and s
	char *csource = strdup(source);
	char *cs = strdup(s);
	strupr(csource);
	strupr(cs);
	//find cs in csource...
	char *result = strstr(csource, cs);
	if (result != NULL)
	{
		//cs is somewhere in csource
		int pos = result - csource;
		result = source;
		result += pos;
	}
	//clean up
	free(csource);
	free(cs);
	return result;
}

wchar_t* wcsustr(wchar_t *source, wchar_t *s)
{
	//make an uppercase copy af source and s
	wchar_t *csource = wcsdup(source);
	wchar_t *cs = wcsdup(s);
	wcsupr(csource);
	wcsupr(cs);
	//find cs in csource...
	wchar_t *result = wcsstr(csource, cs);
	if (result != NULL)
	{
		//cs is somewhere in csource
		int pos = result - csource;
		result = source;
		result += pos;
	}
	//clean up
	free(csource);
	free(cs);
	return result;
}

- Anders

Money talks, but all mine ever says is "Goodbye!"

Nish Nishant23-Dec-02 14:16

23-Dec-02 14:16

Here's mine (ANSI only) :-

char * stristr (const char * string , const char * strCharSet )
{
    char *pstart = (char *) string ;
    char *s1, *s2;      
    
    if ( !*strCharSet  )
        return((char *)string );
    
    while (*pstart)
    {
        s1 = pstart;
        s2 = (char *) strCharSet ;
        
        char c1, c2;
        
        while ( *s1 && *s2  )
        {
            c1 = *s1;
            c2 = *s2;
            
            if( __isascii(c1)  && isupper(c1) )
                c1 = islower(c1);
            
            if( __isascii(c2)  && isupper(c2) )
                c2 = islower(c2);
            
            if(c1 - c2)
                break;
            
            s1++;
            s2++;                       
            
        }
        
        
        if (!*s2)
            return(pstart);
        
        pstart++;
    }
    
    return(NULL);
}

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Anders Molin24-Dec-02 4:06

Anders Molin

24-Dec-02 4:06

Nishant S wrote:
s2 = (char *) strCharSet ;

Why all that casting?

- Anders

Money talks, but all mine ever says is "Goodbye!"

Tim Smith24-Dec-02 4:12

24-Dec-02 4:12

strstr returns a non-const pointer. Sooner or later he has to cast.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Nish Nishant24-Dec-02 4:23

24-Dec-02 4:23

Anders Molin wrote:
Why all that casting?

Yup, you are right. In s2's case I could have declared it as const char*

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Tim Smith24-Dec-02 4:10

24-Dec-02 4:10

c1 = *s1;           
c2 = *s2;
if( __isascii(c1)  && isupper(c1) )
    c1 = islower(c1);
if( __isascii(c2)  && isupper(c2) )
    c2 = islower(c2);

That won't work as is. You should have tolower and not islower. Also, the other tests are redundant.

c1 = tolower (*s1);
c2 = tolower (*s2);

The docs in MSDN aren't totally correct. They say to use isascii and isupper, but that is only true for _tolower, not tolower. However, if you want to keep that code in there, then you can switch to using _tolower which is just a blind macro to add the proper value to convert the case.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Nish Nishant24-Dec-02 4:20

24-Dec-02 4:20

Tim Smith wrote:

That won't work as is. You should have tolower and not islower. Also, the other tests are redundant.

WTF | :WTF:

That was a major GOOF-UP

Thanks Tim!!!!!

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Scott H. Settlemier24-Dec-02 4:28

Scott H. Settlemier

24-Dec-02 4:28

Converting both characters to lower case is wasteful though.
You can get better performance using a test like so:

const int uc='a'-'A';
bool bMatch=c==d || c+uc==d && c>='A' && c<='Z' || c==d+uc && d>='A' && d<='Z';

This usually short-circuits to three comparisons in the majority case of no match. Where this code is located, every bit counts..

Tim Smith24-Dec-02 4:45

24-Dec-02 4:45

Cute...

stricmp uses some assembler tricks to do the following:

if (c1 != c2)
{
   c1 = tolower (c1);
   c2 = tolower (c2);
   //test c1 c2 again
}

With the assebler tricks, it can avoid all the "jumps" associated with short cicuiting.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Scott H. Settlemier24-Dec-02 4:51

Scott H. Settlemier

24-Dec-02 4:51

yeah, there's something to be said for going back to
assembly at really crucial places. Just so long as it
is easy little jobs, it shouldn't make the whole too
unreadable.

Tim Smith24-Dec-02 5:06

24-Dec-02 5:06

Check my new post, the assembler version was slower than a stricmp version using your code. Smile | :)

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Tim Smith24-Dec-02 5:06