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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

Syntax

noexcept( Template:sparam )

Returns an object of type bool.

Explanation

The noexcept operator does not evaluate Template:sparam. The result is false if the Template:sparam 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.
  • Template:rlpt expression
  • Template:rlpt expression when the target type is a reference type, and conversion needs a run time check
  • Template:rlpt expression when argument type is polymorphic class type

In all other cases the result is true.

Keywords

noexcept

Example

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

Template:cpp/language/dcl list noexcept specTemplate:cpp/language/dcl list except spec