C++

参考

<system_error>

error_category

public pure virtual member function
<system_error>

std::error_category::message

virtual string message (int val) const = 0;
Error message
In derived classes, the function returns a string object with a message describing the error condition denoted by val.

In error_category, it is a pure virtual member function.

This function is called both by error_code::message and error_condition::message to obtain the corresponding message in the category. Therefore, numerical values used by custom error codes and error conditions should only match for a category if they describe the same error.

参数

val
标识错误条件的数值。
If the error_category object is the generic_category, this argument is equivalent to an errno value (see errc for a list of standard values).

返回值

A string object with the message.

示例

有关示例，请参见 error_category。

另见

error_category::name
Return category name (public pure virtual member function)