Convert char * to string data type

Why not just read your 10 megs of data directly into tmp2 using stl streams?

Seems like a waste to read 10 megs of data into a char* only to have to allocate another 10 megs by virtue of copying it to an stl string

Be aware that the simple methods of tmp2.assign or tmp2 = tmp1 will work, but they will make a complete copy of the data.  

I don't think there is a way to make your std::string use your char * data in place without making a custom Allocator object, but I'm not sure how to do it.

>>tmp1 now has 1-10 megs of data in it

If tmp1 has NULL terminators mixed in the middle, then you need to use an end pointer position.

Example:
char *tmp1;
int SizeOfDataInTmp1;
string tmp2;

//Set values to tmp1 and SizeOfDataInTmp1

tmp2.assign(tmp1,  tmp1 + SizeOfDataInTmp1);

>>but they will make a complete copy of the data.

Not necessarily, that depends on the implementation. And even if so, 10MB is a piece of cake these days.

FYI:
temp2 = tmp2.insert(0, tmp1);

The  above code will insert into the first position of tmp2, the tmp1 string, until it reaches a NULL terminator.
If this is not working for you, I must assume tmp1 must have NULL terminators within the middle of the data.
In that case, you need to determine the end point of your data, so you can pass it to your std::string.
Then the following should work:
tmp2.insert(0, tmp1, tmp1 + SizeOfDataInTmp1);
or
tmp2.assign(tmp1,  tmp1 + SizeOfDataInTmp1);

Here's an example of how to read stuff from a file right into a string:

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>

using namespace std;

void main()
{
     std::ifstream in;

     in.open("C:\\test.txt");

     if(in.good())
     {
          string buffer;
          std::ifstream::_Iter beginÍter(in);
          std::ifstream::_Iter endIter;

          std::copy(beginÍter, endIter, back_inserter(buffer));

          cout << buffer << endl;

          in.close();
     }
}

>>std::copy(beginÍter, endIter, back_inserter(buffer));

For that method to work std::string would need to have a push_back member function.
But std::string does not.
You could use vector<char> with that method, but that would not give you an std::string object.

      string file_contents;
      copy(istream_iterator<char>(in),istream_iterator<char>(), back_inserter(file_contents));

If you had a fully compliant compiler, you could do the following:
      std::ifstream in;
      in.open("C:\\test.txt");
      string FileContentsInA_String(istream_iterator<char>(in), istream_iterator<char>());

This will not compile on VC++ 6.0

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcstdlib/html/vclrf_string_basicstringpushback.asp

And for GCC: http://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-3.4/classstd_1_1basic__string.html#std_1_1basic__stringa43

>>http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcstdlib/html/vclrf_string_basicstringpushback.asp

That's a link for VC++ .Net

http://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-3.4/classstd_1_1basic__string.html#std_1_1basic__stringa43

That's a link for GNU compiler.

The C++ standard does not have a push_back function for the std::string class with in the basic_string section (21.3 of the ISO/IEC 14882:1998(E) C++ standard)

However, in reading some Newsgroup topics on this, it's seems that the standard does support push_back on std::string indirectly.  And that this support was added late to the standard.
VC++6.0 does not support this, and I'm sure you'll find other compilers that will not support the push_back member function for std::string.


However, IAW the C++ standard, it would seem your code is correct.