Range-based for Loop (C++11)

One-Liner

Syntactic sugar for traversing all elements of a container or array without manually writing iterators, making loop code more concise and less error-prone.

Header

None (language feature)

Core API Quick Reference

Operation	Signature	Description
Read-only traversal	for (auto item : range)	Copies each element to item
Reference traversal	for (auto& item : range)	Accesses elements via lvalue reference (modifiable)
Const reference traversal	for (const auto& item : range)	Avoids copies and prevents modification
Init statement	for (init; auto& item : range)	Executes initialization before the loop (since C++20)
Array traversal	for (auto item : arr)	Supports native arrays of known size

Minimal Example

#include <vector>
#include <iostream>
// Standard: C++11
int main() {
    std::vector<int> v = {1, 2, 3};
    for (const auto& x : v) {
        std::cout << x << ' ';
    }
    return 0;
}

Embedded Applicability: High

• Zero-overhead abstraction: compiles down to code completely equivalent to hand-written iterator or index loops, with no extra runtime cost
• Concise syntax reduces errors caused by out-of-bounds indexing or iterator invalidation
• Combined with constexpr arrays, compile-time traversal is also very practical
• Note: be cautious of lifetime issues when traversing member functions that return temporary objects (this is UB prior to C++23)

Compiler Support

GCC	Clang	MSVC
4.6	3.0	2010

See Also

• cppreference: Range-based for loop

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