# Templates
___
## Knowledge check
### Template type deduction
template <typename T>
void copy(T arg) {}
template <typename T>
void reference(T& arg) {}
template <typename T>
void universal_reference(T&& arg) {}
int main() {
int number = 4;
copy(number); // int
copy(5); // int
reference(number); // int&
reference(5); // candidate function [with T = int] not viable: expects an l-value for 1st argument
universal_reference(number); // int&
universal_reference(std::move(number)); // int&&
universal_reference(5); // int&&
}
___
## Knowledge check
```cpp
void foo(int && a); // r
void foo(int & a); // l
int a = 5;
```
Which of above functions will be called by below snippets?
* foo(4);
* r
* foo(a);
* l
* foo(std::move(a));
* r
* foo(std::move(4));
* r (move is redundant)
___
## Knowledge check
```cpp
template
void foo(T && a); // r
template
void foo(T & a); // l
int a = 5;
```
Which of above functions will be called by below snippets?
* foo(4);
* r
* foo(a);
* l
* foo(std::move(a));
* r
___
## Knowledge check
```cpp
template
void foo(T && a); // r
int a = 5;
```
What will happen now?
* foo(4);
* r
* foo(a);
* r
* foo(std::move(a));
* r