Read CString from buffer with unknown length?

Question

Let's say I have a file. I read all the bytes into an unsigned char buffer. From there I'm trying to read a c string (null terminated) without knowing it's length.

I tried the following:

char* Stream::ReadCString()
{
    char str[0x10000];
    int len = 0;
    char* pos = (char*)(this->buffer[this->position]);
    while(*pos != 0)
        str[len++] = *pos++;
    this->position += len+ 1;
    return str;
}

I thought I could fill up each char in the str array as I went through, checking if the char was null terminated or not. This is not working. Any help?

this->buffer = array of bytes
this->position = position in the array

Are there any other methods to do this? I guess I could run it by the address of the actual buffer: str[len++] = *(char*)(this->buffer[this->position++]) ?

Update: My new function:

char* Stream::ReadCString()
{
    this->AdvPosition(strlen((char*)&(this->buffer[this->position])) + 1);
    return (char*)&(this->buffer[this->position]);
}

and calling it with:

printf( "String: %s\n", s.ReadCString()); //tried casting to char* as well just outputs blank string

Example File:

Answer 1

Check this:

#include <cstring>
#include <iostream>

class   A
{
  unsigned char buffer[4096];
  int   position;

public:
  A() : position(0)
  {
    memset(buffer, 0, 4096);
    char        *pos = reinterpret_cast<char*>(&(this->buffer[50]));
    strcpy(pos, "String");
    pos = reinterpret_cast<char*>(&(this->buffer[100]));
    strcpy(pos, "An other string");
  }

   const char *ReadString()
  {
    if (this->position != 4096)
      {
        while (std::isalpha(this->buffer[this->position]) == false && this->position != 4096)
               this->position++;
        if (this->position == 4096)
          return 0;
        void    *tmp = &(this->buffer[this->position]);
        char    *str  = static_cast<char *>(tmp);
        this->position += strlen(str);
        return (str);
      }
    return 0;
  }

};

The reintrepret_cast are only for the init, since you are reading from a file

int     main()
{
  A     test;

  std::cout << test.ReadString() << std::endl;
  std::cout << test.ReadString() << std::endl;
  std::cout << test.ReadString() << std::endl;
}

http://ideone.com/LcPdFD

Edit I have changed the end of ReadString()