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noexcept operator (since C++11)

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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.

Contents

[edit] Syntax

noexcept( expression )

Returns an object of type bool.

[edit] 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 conversion needs a run time check
  • typeid expression when argument type is polymorphic class type

In all other cases the result is true.

[edit] Keywords

noexcept

[edit] Example

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

[edit] See also

noexcept specifier requires a function to not throw any exceptions (C++11) [edit]
exception specification specifies what exceptions are thrown by a function (deprecated) [edit]