[Boost-users] [lambda]How to use the member of placeholder in std algorithm?

Subject: [Boost-users] [lambda]How to use the member of placeholder in std algorithm?
From: Ç®ÏþÃ÷ (kyleqian_at_[hidden])
Date: 2009-02-27 00:53:56

I have a struct:
struct Coordinate {
 double x, y, z;
};
There is no any operator definition for it.

I want to sort a array of this struct with 3 elements by comparing the Z
value, so:
Coordinate coords[3];
.......
std::sort(coords, coords+3, _1 < _2);
What should I write to replace "_1 < _2" here? How can I reference the Z
member of _1 and _2?
I hope I can sort this array without defining any new function.

thanks!