Question: I want to fetch the places of 20 meters using current latitude and longitude and display in list(without showing in google map).

Please help me.

Answer: 
This is a typical application for a [quadtree](http://en.wikipedia.org/wiki/Quadtree). The quadtree facilitates lookup of the m points lying in your rectangle in O(log(n) + m), where n is the total number of points.

Edit: Your approach using the map is not nearly as efficient. For randomly distributed points, it would have an O(sqrt(n)) average complexity, and O(n) worst-case.
If you use a std::map of points the lookup will always be O(log N) where N is the number of points you have.

Your other option would be to divide your search space into buckets and put your point into buckets. You then calculate in your rectangle:

* any buckets for which all the points are inside your rectangle
* any for which there is some overlap.

For those that there is some overlap you can then look up in your collection which is O(M) if you use the right collection type per bucket, but M should be smaller than N. It may even be that M rarely exceeds a handful in which case you can probably check them linearly.

Working out which buckets overlap is a constant time operation but you have to run through these linearly (even to check if they are empty) so having too many of them may also be an issue.