inserting std::strings in to a std::map

Question

I have a program that reads data from a file line-by-line. I would like to copy some substring of that line in to a map as below:

std::map< DWORD, std::string > my_map;
DWORD index;         // populated with some data
char buffer[ 1024 ]; // populated with some data
char* element_begin; // points to some location in buffer
char* element_end;   // points to some location in buffer > element_begin

my_map.insert( std::make_pair( index, std::string( element_begin, element_end ) ) );

This std::map<>::insert() operation takes a long time (It doubles the file parsing time). Is there a way to make this a less expensive operation?

Thanks, PaulH

Edit: to be more specific, I want to know that I'm doing the minimum number of copy operations to get the data from the file in to the map.

Answer 1

Do you really need a map here? As far as I can see in your example you only want to store an index as key value that is, as I suppose, simply incremented for each insertion. You could accomplish this with an std::vectorwhich is know to be the fastest container. Just use push_backand access the value with at(index).