c++中的std::any怎么用_c++任意类型存储any用法示例

#include <iostream>
#include <any>
#include <string>
<p>int main() {
std::any data;</p><pre class='brush:php;toolbar:false;'>// 存储整数
data = 42;
std::cout << "int: " << std::any_cast<int>(data) << '\n';

// 存储字符串
data = std::string("Hello World");
std::cout << "string: " << std::any_cast<std::string>(data) << '\n';

// 存储浮点数
data = 3.14;
std::cout << "double: " << std::any_cast<double>(data) << '\n';

return 0;

if (data.type() == typeid(int)) {
    std::cout << "It's an int: " << std::any_cast<int>(data) << '\n';
} else {
    std::cout << "Not an int\n";
}
<p>// 指针方式检查和访问（更安全）
double<em> dptr = std::any_cast<double>(&data);
if (dptr) {
std::cout << "Got double via pointer: " << </em>dptr << '\n';
} else {
std::cout << "Not a double\n";
}</p>

struct Person {
    std::string name;
    int age;
    Person(std::string n, int a) : name(n), age(a) {}
};
<p>// 使用
std::any p = Person("Alice", 25);
Person person = std::any_cast<Person>(p);
std::cout << person.name << ", " << person.age << '\n';</p>

data.reset();
if (!data.has_value()) {
    std::cout << "No value stored.\n";
}