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Calculates the length of a geometry.
The free function length calculates the length (the sum of distances between consecutive points) of a geometry. It uses the default strategy, based on the coordinate system of the geometry.
template<typename Geometry> default_length_result<Geometry>::type length(Geometry const & geometry)
| Type | Concept | Name | Description | 
|---|---|---|---|
| Geometry const & | Any type fulfilling a Geometry Concept | geometry | A model of the specified concept | 
The calculated length
Either
            #include <boost/geometry.hpp>
          
Or
            #include <boost/geometry/algorithms/length.hpp>
          
The function length implements function Length from the OGC Simple Feature Specification.
| Case | Behavior | 
|---|---|
| pointlike (e.g. point) | Returns 0 | 
| linear (e.g. linestring) | Returns the length | 
| areal (e.g. polygon) | Returns 0 | 
Linear
The following simple example shows the calculation of the length of a linestring containing three points
#include <iostream> #include <boost/geometry.hpp> #include <boost/geometry/geometries/linestring.hpp> #include <boost/geometry/geometries/point_xy.hpp> int main() { using namespace boost::geometry; model::linestring<model::d2::point_xy<double> > line; read_wkt("linestring(0 0,1 1,4 8,3 2)", line); std::cout << "linestring length is " << length(line) << " units" << std::endl; return 0; }
Output:
linestring length is 15.1127 units