Using default argument in the template function.

[=?gb2312?B?wfXquw==?=]

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.

[Barry]

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>();

[nevergone]

On 8 1 , 12 20 , <[e-mail]:

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>();