Question

I am not using boost libraries. How can i do this using STL?

class Files
{

private:
   bool isSame(FileID f1, FileId f2)
   { 
      if(f1.getId()==f2.getId())
        return true;
      return false;
   }

public:
   vector<FileId> mod_files;

    void update()
    {
      FildId f = getFileId();
      vector<FildId>::const_iterator found = find_if(mod_files.begin(), mod_files.end(),          ???);
    }

};

I would like to pass isSame as the third argument to find_if function, and bind “f” to the isSame’s second argument.

Answer 1

In C++11 that’s simply:

std::bind(&Files::isSame, this, f);

In good old C++03 there is no mem_fun that takes 2 arguments, so you would have to do the binding on your own:

class is_same_pred
{
public:
    // unary function typedefs

    explicit is_same_pred(Files& files, FileId f1) : _files(files), _f1(f1) {}

    bool operator()(FileId f2) const { return _files.isSame(_f1, f2); }

private:
    Files& _files;
    FileId _f1;
};

Where isSame is accessible to is_same_pred, and later use it like this:

is_same_pred(this, f);

All that said and done, you would be better off defining isSame as a static or free-function:

bool isSame(FileId f1, FileId f2){ ... }

std::bind1st(std::ptr_fun(&isSame), f);