Is it possible to specify only some template parameters when calling a function template and let the compiler deduce the others

Question

Consider the following function template:

template <typename T1, typename T2>
void foo(T1 a, T2 b){// Do something.}

Now assume that I want T1 to be int, but T2 to be deduced by the compiler depending on the type of b. Something like foo<int,...>(1,b). Is it possible?

Thanks!

Answer 1

Yes!

foo<int>(1, b);

But in that example above there is no benefit. The difference is visible if your first argument would not already be deduced to int:

foo<int>(3.2f, b);
//       ^^^^ Implicit conversion