std::bad_variant_access
STD：不好[医]变体[医]存取
| Defined in header | | |
|---|---|---|
| class bad_variant_access : public std::exception | | (since C++17) |
std::bad_variant_access在下列情况下引发的异常的类型：
std::get(std::variant)使用与当前活动选项不匹配的索引或类型调用。
std::visit调用访问一个变体valueless_by_exception
成员函数
| (constructor) | bad_variant_access() (public member function) |
|---|
STD：不好[医]变体[医]准入：：糟糕[医]变体[医]接入%28%29
| bad_variant_access( | | |
|---|
构造一个新的实例。std::bad_variant_access...
参数
%280%29
例外
noexcept规格：
noexcept
继承自STD：例外
成员函数
| (destructor) virtual | destructs the exception object (virtual public member function of std::exception) |
|---|---|
| what virtual | returns an explanatory string (virtual public member function of std::exception) |
例
二次
#include <variant>
#include <iostream>
int main()
{
std::variant<int, float> v;
v = 12;
try {
std::get<float>(v
}
catch(const std::bad_variant_access& e) {
std::cout << e.what() << '\n';
}
}
二次
可能的产出：
二次
bad_variant_access
二次
另见
| std::get(std::variant) (C++17) | reads the value of the variant given the index or the type (if the type is unique), throws on error (function template) |
|---|---|
| visit (C++17) | calls the provided functor with the arguments held by one or more variants (function template) |
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