Range-Based for Loop (C++11)

In a nutshell

Syntactic sugar that lets us iterate over every element of a container or array without hand-writing iterators, making loop code more concise and less error-prone.

Header file

None (language feature)

Core API Cheat Sheet

Operation	Signature	Description
Read-only traversal	for (auto item : range)	Copies each element into 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)	Runs initialization before the loop starts (since C++20)
Array traversal	for (auto item : arr)	Works with 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 to code fully equivalent to a hand-written iterator or index loop, with no extra runtime cost
• The concise syntax cuts down on bugs caused by out-of-bounds indices or invalidated iterators
• Also very practical for compile-time traversal of constexpr arrays
• Caution: when the range comes from a member function returning a temporary, watch out for lifetime issues (UB before C++23)

Compiler Support

GCC	Clang	MSVC
4.6	3.0	2012

See Also

• cppreference: Range-based for loop

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