Iteration over std::vector: unsigned vs signed index variable

In the specific case in your example, I'd use the STL algorithms to accomplish this.

#include <numeric> 



sum = std::accumulate( polygon.begin(), polygon.end(), 0 );

For a more general, but still fairly simple case, I'd go with:

#include <boost/lambda/lambda.hpp>

#include <boost/lambda/bind.hpp>



using namespace boost::lambda;

std::for_each( polygon.begin(), polygon.end(), sum += _1 );

4 years ago

A call to vector<T>::size() returns a value of type std::vector<T>::size_type, not int, unsigned int or otherwise.

Also generally iteration over a container in C++ is done using iterators, like this.

std::vector<T>::iterator i = polygon.begin();

std::vector<T>::iterator end = polygon.end();



for(; i != end; i++){

    sum += *i;

}

Where T is the type of data you store in the vector.

Or using the different iteration algorithms (std::transform, std::copy, std::fill, std::for_each et cetera).

4 years ago

Use size_t :

for (size_t i=0; i < polygon.size(); i++)

4 years ago