公共成员函数 (public member function)
<system_error>
const error_category& category() const noexcept;
获取类别 (Get category)
返回值
对从 错误类别 派生的类型的一个不可复制的对象的引用。
示例
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// error_condition observers: value, category and message
#include <iostream> // std::cout, std::ios
#include <system_error> // std::system_error, std::error_condition
#include <fstream> // std::ifstream
#include <string> // std::string
int main()
{
std::ifstream is;
is.exceptions (std::ios::failbit);
try {
is.open ("unexistent.txt");
} catch (std::system_error excptn) {
std::error_condition cond = excptn.code().default_error_condition();
std::cout << "Exception caught (system_error):\n";
std::cout << "Value: " << cond.value() << '\n';
std::cout << "Category: " << cond.category().name() << '\n';
std::cout << "Message: " << cond.message() << '\n';
}
return 0;
}
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可能的输出
Exception caught (system_error):
Value: 1
Category: iostream
Message: iostream stream error
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