Question

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Advantages of std::for_each over for loop

So I was playing around with some C++11 features and I’m curious as to why std::for_each is beneficial. Wouldn’t it be easier and look cleaner to do a for loop or is it because I’m so used to doing it this way?

#include <iostream>
#include <tuple>
#include <vector>
#include <algorithm>

typedef std::tuple<int, int> pow_tuple;

pow_tuple pow(int x)
{
    return std::make_tuple(x, x*x);
}

void print_values(pow_tuple values)
{
    std::cout << std::get<0>(values) << "\t" << std::get<1>(values) << std::endl;
}

int main(int argc, char** argv)
{
    std::vector<int> numbers;
    for (int i=1; i < 10; i++)
        numbers.push_back(i);
    std::for_each(numbers.begin(), numbers.end(),
        [](int x) { print_values(pow(x)); }
        );

    std::cout << "Using auto keyword:" << std::endl;
    auto values = pow(20);
    print_values(values);
    return 0;
}

Answer 1

It depends somewhat on the local coding conventions, but there are two
potential advantages. The first is that it states clearly that the code
iterates over all of the elements in the sequence; unless the local
coding conventions say otherwise (and they are enforced), you have to
consider that some cowboy programmer might have inserted a break. The
second is that it names the operation you are performing on each
element; this once can easily be handled by calling a function in the
loop, and of course, really trivial operations may not need a name.

There’s also the advantage, at least if you aren’t yet using C++11, that
you don’t have to spell out the iterator types; the spelled out iterator
types create a lot of verbiage, in which the important logic can get
lost or overlooked.