Question

Having this vector

vector<int> v{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

how can I compute the sum of the first half of it (which is 15) using the accumulate function?

Can I do this using the for loop with only the iterators (not numerical indexes)?

Answer 1

You can

accumulate(v.begin(), v.begin()+int(v.size()/2), 0)

if v is your vector.

You can also write a loop:

int sum = 0;
for (vector<int>::iterator it = v.begin(); it != v.begin+int(v.size()/2); ++it) {
    sum += *it;
}