A function returns to its caller by the return statement.
A return statement with neither an expression nor a braced-init-list can be used only in functions that do not return a value, that is, a function with the return type void, a constructor ([class.ctor]), or a destructor ([class.dtor]). A return statement with an expression of non-void type can be used only in functions returning a value; the value of the expression is returned to the caller of the function. The value of the expression is implicitly converted to the return type of the function in which it appears. A return statement can involve the construction and copy or move of a temporary object ([class.temporary]). [ Note: A copy or move operation associated with a return statement may be elided or considered as an rvalue for the purpose of overload resolution in selecting a constructor ([class.copy]). — end note ] A return statement with a braced-init-list initializes the object or reference to be returned from the function by copy-list-initialization ([dcl.init.list]) from the specified initializer list. [ Example:
std::pair<std::string,int> f(const char* p, int x) {
return {p,x};
}
— end example ]
Flowing off the end of a function is equivalent to a return with no value; this results in undefined behavior in a value-returning function.
A return statement with an expression of type void can be used only in functions with a return type of cv void; the expression is evaluated just before the function returns to its caller.