c++ for_each() and object functions

Question

I have an assignment that is the following:

For a given integer array, find the sum of its elements and print out the final result, but to get the sum, you need to e

Answer 1

vector<int> v(array[0], array[10]);

This doesn't do what you want. array[0] is the first value (1). array[10] is in invalid access past the end of your array. To pass pointers to the vector constructor, you want:

vector<int> v(array, array+10);

Answer 2

If you really want to compute the sum, std::accucumulate is what you want, not for_each

Answer 3

I know you were told to use for_each, but I would actually do this - perhaps an alternative for extra credit ;-)

#include <numeric>
using namespace std;

int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

int sum = accumulate(array, array + (sizeof(array) / sizeof(int)), 0);

accumulate is expressly designed for summing the elements of an iterable range.

Answer 4

why not just:

for_each( array, array+10, myFunction);

I'm quite sure that int* can be used as iterator

EDIT: just checked this, it can indeed

Answer 5

You're not constructing the vector right. The constructor that takes two integers is

vector(size_type _Count, const Type& _Val);

So _Count is 1 and _Value is an undefined value past the end of the array.

Answer 6

array has indexes 0..9, so array[9] = 10

if array[10] doesnt throw an error it will contain erroneous data, causing this problem.