Using default argument in the template function. - c++

Áõê» wrote:
> Hi folks,
>
> I am trying to add a default argument to a template function in a
> template class, here is the code snippet:
>
> template<typename T>
> class Test {
> template<typename U>
> friend void doSomething(U level);
> };
>
> template<typename U>
> void doSomething(U level = 0) {
> cout << "Here I am doing something\n";
> }
>
> int main() {
> doSomething();
> }
>
> An error araise at the compile time:
>
> error C2783: 'void doSomething(U)' : could not deduce template
> argument for 'U'
>
> How can I define such a template function taking a default argument?
> Thank you.
>

The actual argument passed into the function is used to instantiate the
function template, so if you really want to do in the default argument
way, I think you have explicitly write the template param, like the
following:

doSomething<your type>();

On 8 1 , 12 20 , <leomayleo...> wrote:
> Hi folks,
>
> I am trying to add a default argument to a template function in a
> template class, here is the code snippet:
>
> template<typename T>
> class Test {
> template<typename U>
> friend void doSomething(U level);
>
> };
>
> template<typename U>
> void doSomething(U level = 0) {
> cout << "Here I am doing something\n";
>
> }
>
> int main() {
> doSomething();
>
> }
dosomething<yourtype>();