How to use structured bindings to unpack data in C 17? (Code Example)-C++-php.cn

Table of Contents

Unpack a std::tuple

Unpack a simple struct (with public members)

Unpack a std::array

Bind by reference or const reference

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How to use structured bindings to unpack data in C 17? (Code Example)

Charles William Harris

Dec 27, 2025 am 01:46 AM

结构化绑定允许直接解包元组、结构体和数组为命名变量；例如auto [x, y, z] = t;可将tuple元素分别推导为int、std::string和double类型。

How to use structured bindings to unpack data in C 17? (Code Example)

Structured bindings let you unpack tuples, structs, and arrays directly into named variables—no std::get, no manual member access, no boilerplate.

Unpack a `std::tuple`

You can destructure a tuple in one line using auto [a, b, c]. The compiler deduces types and binds each element to a variable.

std::tuple t{42, "hello", 3.14};
auto [x, y, z] = t;
// x is int, y is std::string, z is double
std::cout

Unpack a simple struct (with public members)

For aggregates or classes with public non-static data members and no user-defined constructors, structured bindings work out of the box.

struct Point {
int x;
int y;
};

Point p{10, 20};
auto [px, py] = p;
// px and py are copies of p.x and p.y
std::cout

Unpack a `std::array`

Arrays behave like tuples: size is known at compile time, so binding works cleanly.

std::array<:string> names = {"Alice", "Bob"};
auto [first, second] = names;
// first and second are std::string
std::cout

Bind by reference or const reference

Add & or const &amp; to avoid copying—especially useful for large objects or when you need to modify the original.

std::vector<:string> v = {"one", "two"};
auto& [a, b] = v; // error! vector isn't a tuple-like type

// But for arrays or tuples:
std::array<:string> arr = {"X", "Y"};
auto& [ref1, ref2] = arr;
ref1 = "changed"; // modifies arr[0]

Just remember: the type must be tuple-like (specialized std::tuple_size and std::get) or an aggregate with accessible members. No inheritance, no private fields, no user-defined constructors unless you provide the right customization points.

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