using class local type definition in constructor declaration

Question

I am trying to use a class local type definition in a constructor declaration. both the classes are templates, here is the code.

template < typename T>
class complexType
{
    public:
    using value_type = T;
    complexType( T t ) {}
};


template <typename containedType >
class container
{
    public:
    container ( containedType::value_type v ) { return; }
    //container ( int v ) { return; }
};

int main(int ac, char **av)
{
    container <complexType<int>> c(100);
    return 0;
}

if i use the second constructor definition which is being passed an int, the code builds fine. i cannot reason why the code won't build.

Possible duplicate of [Where and why do I have to put the "template" and "typename" keywords?](https://stackoverflow.com/questions/610245/where-and-why-do-i-have-to-put-the-template-and-typename-keywords) — n. m. could be an AI, Dec 14 '18 at 07:10

score 1 · Accepted Answer · answered Dec 14 '18 at 07:08

1

value_type is dependent name, which depends on template argument, in such case you need to use typename to indicate that value_type is type:

template <typename containedType >
class container
{
    public:
    container ( typename containedType::value_type v ) { return; }
                ^^^^^^^ 
    //container ( int v ) { return; }
};

answered Dec 14 '18 at 07:08

rafix07

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Thanks alot it worked like a charm. need to do more research on this typename – Ravikumar Tulugu Dec 14 '18 at 07:16

using class local type definition in constructor declaration

1 Answers1