C++: What is the difference between std::for_each and range-based for?

for_each — algorithm. range-based for — language feature.

std::for_each:

• STL algorithm.
• Takes function object.
• Can be parallelized (C++17).

1std::vector<int> v = {1, 2, 3};
2
3// Lambda
4std::for_each(v.begin(), v.end(),
5    [](int& x) { x *= 2; }
6);
7
8// Function object
9struct Double {
10    void operator()(int& x) const { x *= 2; }
11};
12std::for_each(v.begin(), v.end(), Double());

Range-based for:

• Language syntax.
• Simpler, more readable.

1for (int& x : v) {
2    x *= 2;
3}

Key differences:

• for_each — can be parallel (C++17).
• range-based — simpler, more readable.
• for_each — returns function object (can accumulate).
• range-based — no return value.