Actually there are quite a few methods.

int sum_of_elems = 0;

C++03

Classic for loop:

for(std::vector

sum_of_elems += *it;

Using a standard algorithm:

#include

sum_of_elems = std::accumulate(vector.begin(), vector.end(), 0);

Important Note: The last argument’s type is used not just for the initial value, but for the type of the result as well. If you put an int there, it will accumulate ints even if the vector has float. If you are summing floating-point numbers, change 0 to 0.0 or 0.0f (thanks to nneonneo). See also the C++11 solution below.

C++11 and higher

b. Automatically keeping track of the vector type even in case of future changes:

#include

sum_of_elems = std::accumulate(vector.begin(), vector.end(),

decltype(vector)::value_type(0));

Using std::for_each:

std::for_each(vector.begin(), vector.end(), [&] (int n) {

sum_of_elems += n;

});

Using a range-based for loop (thanks to Roger Pate):

for (auto& n : vector)

sum_of_elems += n;

The easiest way is to use std:accumulate of a vector

#include

cout << accumulate(A.begin(), A.end(), 0);