Question

I need to search through a chunk of memory for a string of characters, but several of these strings have every character null separated, like this:
“I. .a.m. .a. .s.t.r.i.n.g”
with all of the ‘.’s being null characters. My problem comes from actually getting this into memory. I’ve tried several ways, for instance:

 char* str2; 
 str2 = (char*)malloc(sizeof(char)*40);   
 memcpy((void*)str2, "123\0567\09abc", 12);    

Will put the following into the memory that str2 points to: 123.7.9abc..
Something like
str2 = "123456789\0abcde\054321";
Will have str2 pointing to a block of memory that looks like 123456789.abcde,321 , wherein the ‘.’ is a null character, and the ‘,’ is an actual comma.

So clearly inserting null characters into cstrings doesn’t work as easily as I thought it did, like inserting a newline character. I encountered similar difficulties trying this with the string library as well. I could do separate assignments, something like:

 char* str;    
 str = (char*)malloc(sizeof(char)*40);  
 strcpy(str, "123");  
 strcpy(str+4, "abc");  
 strcpy(str+8, "ABC");  

But that is certainly not preferable, and I believe the problem lies in my understanding of how c-style strings are stored in memory. Clearly “abc\0123” doesn’t actually go into memory as 61 62 63 00 31 32 33 (in hex). How is it stored, and how can I store what I need to?

(I also apologize for not having set the code in blocks, this is my first time posting a question, and somehow “four spaced” is more difficult than I can handle apparently. Thank you, Luchian. I see more newlines were needed.)

Answer 1

If every other char contains a null, then almost certainly you actually have UTF-16 encoded strings. Process them accordingly and your problems will disappear.

Assuming you are on Windows, where UTF-16 is common, you would use wchar_t* rather than char* to hold such strings. And you would use wide char string processing functions to operate on such data. For example, use wcscpy rather than strcpy and so on.