Question

It is well known that cin is not typesafe (e.g. cin >> integer; and entering “fifty five” will cause it to flip out). I have seen many not-so-elegant ways to hand this, such as getlining a string and using sstream to convert it to a number, or looping with cin.fail() and clearing the stream and reentering it, etc. Is there any library or anyway to overload the extraction operator to make cin automatically typesafe?

Answer 1

e.g. cin >> integer; and entering “fifty five” will cause it to flip out

No, this will not cause it to “flip out;” it will cause the fail state of the stream to be set, just like with any other stream. This doesn’t mean that std::cin is not type-safe.

One option for handling errors reading from a stream would be to write a function template that performs the extraction, tests whether it succeeded, resets the error state on the stream if appropriate, and returns whether the extraction succeeded along with the result.