Why do I need to explicitly write the 'auto' keyword?

c++ c++11 auto
Farsan Rashid picture Farsan Rashid · May 23, 2018 · Viewed 9.3k times · Source

I am moving towards C++11 from C++98 and have become familiar with the auto keyword. I was wondering why we need to explicitly declare auto if the compiler is able to automatically deduce the type. I know C++ is a strongly typed language and this is a rule but was it not possible to achieve the same outcome without explicitly declaring a variable auto?

Answer

Bathsheba picture Bathsheba · May 23, 2018

Dropping the explicit auto would break the language:

e.g.

int main()
{
    int n;
    {
        auto n = 0; // this shadows the outer n.
    }
}

where you can see that dropping the auto would not shadow the outer n.

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