noexcept operator (since C++11)

 

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noexcept operator (C++11)

 

The noexcept operator performs a compile-time check that returns true if an expression is declared to not throw any exceptions.

It can be used within a function template's noexcept specifier to declare that the function will throw exceptions for some types but not others.

Syntax

noexcept( expression )

Returns an object of type bool.

Explanation

The noexcept operator does not evaluate expression. The result is false if the expression contains at least one of the following potentially evaluated constructs:

• call to any type of function that does not have non-throwing exception specification, unless it is a constant expression.
• throw expression.
• dynamic_cast expression when the target type is a reference type, and conversion needs a run time check
• typeid expression when argument type is polymorphic class type

In all other cases the result is true.

Keywords

noexcept

Example

Run this code

template <class T>
void self_assign(T& t) noexcept(noexcept(t = t))
{ // self_assign is noexcept if and only if T::operator= is noexcept
    t = t;
}

See also

noexcept specifier(C++11)	specifies whether a function could throw exceptions
Dynamic exception specification(until C++17)	specifies what exceptions are thrown by a function (deprecated in C++11)