memstr

[kevincwong]

Hi, I have a binary string. I need to search certain characters. I used to use "memstr" (obtain fist substring from string) on Unix. Is there anything similar to that available from MFC? Thanks, Kevin

[Rage]

If your are using CStrings, yes, CString::Find ~RaGE();

[kakan]

strstr or _strstr

[vikas amin]

Use the CString to store the binary data & use Find (..) member fuction to find the charaters. :cool: Vikas Amin Embin Technology Bombay vikas.amin@embin.com

[James R Twine]

There is nothing exactly like memstr(...) in MFC or in the MS VC++ RTL.  The closest things are strstr(...) and and functions like CString::Find(...).    However, these might not work as you expect, because you said "binary string", and that usually means that NUL characters can be expected in other locations than the end of the string.    Other than taking an existing implementation and copying the source or writing your own implementation, a Q&D way would be to store the locations of all of the non-terminating NUL characters and convert them to some other character and then use a function like strstr(...) (with the strings modified as specified above).    After locating your substrings, you can convert them back by replacing the NULs you replaced before.    Peace! -=- James

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[PJ Arends]

As was mentioned before, strstr is the closest thing, but it is limited in that NULL characters terminate the buffers. So I have used this code:

#include <string.h>

char * _memmem(const char *mem, size_t mem_size, const char *sub, size_t sub_size)
{
// returns a pointer of the first occurance of a sub-buffer in a memory buffer
// returns NULL if the sub-buffer was not found
// is not limited by embedded NULLs in either the memory buffer or the sub-buffer
//
// Parameters:
// mem - The memory buffer to scan
// mem_size - The size, in bytes, of the memory buffer
// sub - The sub buffer to find
// sub_size - The size, in bytes, of the sub buffer

char \*ret = NULL;
char \*ptr = const\_cast<char \*>(mem);
while (ptr && !ret)
{
    ptr = reinterpret\_cast<char \*>(memchr(ptr, \*sub, mem\_size - (sub\_size - 1) - (int)(ptr - mem)));
    if (ptr)
    {
        if (!memcmp(ptr, sub, sub\_size))
            ret = ptr;
        ++ptr;
    }
}

return ret;

}

[edit] cleaned up the code a little [/edit]

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