How to put std::set into std::map

Question

I declared std: map below:

std::map<std::string, std::set<unsigned char*>> FilesMap;

int InsertData(unsigned char* name)
{
  // here i try to insert pair with name above and clear std::set
   FilesMap.insert(std::pair<std::string, std::set<unsigned char*>>(std::string((char*)name), std::set<unsigned char*>()));
}

But I have many errors like:

Error 16 error C2676: binary '<': 'const std::string' does not define this operator or a conversion to a type acceptable to the predefined operator c: \program files (x86)\microsoft Visual Studio 10.0\vc\include\xfunctional

What am I doing wrong?

Answer 1

First of all, this horribly long line

FilesMap.insert(std::pair<std::string, std::set<unsigned char*>>(std::string((char*)name), std::set<unsigned char*>()));

can be simplified if you use std::make_pair function, which will deduce template arguments.

FilesMap.insert(std::make_pair(std::string(reinterpret_cast<char*>name)), std::set<unsigned char*>()));

Second, you could make a typedef for your set so as to simplify the above line even more

typedef std::set<unsigned char*> mySetType;
std::map<std::string, mySetType>> FilesMap;
 FilesMap.insert(std::make_pair(std::string(reinterpret_cast<char*>name)), MySetType()));

And lastly, and most importantly, I believe the reason that the compiler is unable to find a suitable operator < for std::string is that you forgot to #include<string>

Answer 2

A requirement for using std::map, is that the key type has to have an operator < . It seems you are getting an error with regards to std::string not having this operator. Make sure you have included the string header #include <string>.