How to get the address of the std::vector buffer start most elegantly?

Question

I want to use std::vector for dynamically allocating memory. The scenario is:

int neededLength = computeLength(); // some logic here

// this will allocate t         


        

Answer 1

Elegant way would be to change callFunction or to write wrapper for it as follows:

// legacy function
void callFunction( TCHAR* buf, int buf_size)
{
  // some code
}

// helpful template
void callFunction( std::vector::iterator begin_it, std::vector::iterator end_it )
{
  callFunction( &*begin_it, std::distance( begin_it, end_it ) );
}

// somewhere in the code
int neededLength = computeLength();
std::vector buffer( neededLength );
callFunction( buffer.begin(), buffer.end() );

You could even make wrapper for all such functions (with different types, not only TCHAR):

template
void callFunction( T begin_it, typename std::vector::iterator end_it )
{
  callFunction( &*begin_it, std::distance( begin_it, end_it ) );
}

Type T will be properly deduced (as std::vector) and you'll be able still write callFunction( buffer.begin(), buffer.end() );.

Note that you cannot declare template function as void callFunction( typename std::vector::iterator begin_it, typename std::vector::iterator end_it ) as someone proposed recently as an edit to this answer, because in that case you will get the deducion error.