std::any是C 17引入的類型安全容器，可存儲任意類型的單個值，需包含
頭文件；支持通過賦值或初始化存入不同類型的值，使用std::any_cast安全訪問，支持異常和指針形式的類型檢查，結(jié)合has_value和type可判斷值存在性與類型信息，適用于配置系統(tǒng)等異構(gòu)類型場景，但存在性能開銷且要求存儲類型可復(fù)制，建議謹(jǐn)慎使用以保持代碼清晰與效率。
std::any is a type-safe container introduced in C 17 that can hold a single value of any type. It's part of the \
Include the Required Header
To use std::any, include the \
#include
Create and Assign Values
You can create an std::any object and assign values of different types to it. The assignment replaces the current value.
std::any data;data = 42; // int
data = std::string{"Hello"}; // string
data = 3.14; // double
You can also initialize directly:
std::any name = std::string{"Alice"};std::any age = 30;
std::any height = 5.7;
Access the Stored Value
To retrieve the value stored in an std::any, use std::any_cast. This is type-safe: if the requested type doesn’t match, it throws std::bad_any_cast.
try {???int value = std::any_cast
???std::cout } catch (const std::bad_any_cast&) {
???std::cout }
You can also use pointer-style casting to avoid exceptions:
double* ptr = std::any_castif (ptr) {
???std::cout } else {
???std::cout }
Check and Manage Type Safety
You can check whether an std::any contains a value using has_value(), and get its type with type(), which returns a const std::type_info&.
if (data.has_value()) {???std::cout }
This is helpful when debugging or validating input from generic interfaces.
Use Cases and Limitations
std::any is ideal for scenarios like configuration systems, plugin interfaces, or message passing where types vary. However, it comes with overhead — both in performance and safety. Overuse can make code harder to maintain and debug.
Avoid storing large objects by value; prefer wrapping them in smart pointers if needed:
std::any big_data = std::make_sharedAlso, note that types stored in std::any must be copy-constructible.
Basically, std::any gives flexibility with runtime type erasure, but should be used thoughtfully to preserve clarity and performance.
以上是如何使用 std::any 保存 C 中的任何類型的詳細(xì)內(nèi)容。更多信息請關(guān)注PHP中文網(wǎng)其他相關(guān)文章！
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