Some cases in which C + + defines a formal parameter as a reference type

1. If you want to modify the value of an argument through a function call, you should define the parameter as a reference type;

For example, to exchange a two-digit value with the Swap function, you should define the parameter as a reference type

2. To obtain multiple result values through a function call, you can also use reference parameters;

3. When passing large objects to a function, to avoid copying arguments to adjust efficiency and to use class types that cannot be copied

(whose copy constructor is a private class type) as the formal parameter type, should also the parameter is defined as a reference type.

However, the purpose of using the formal parameter is to avoid copying the arguments, The formal parameter should be defined as a const reference;

4. If you do not need to modify the value of an argument through a function call, you should not define the parameter as a reference type;

For example, in an absolute function abs, a formal parameter should not be defined as a reference type.

Some cases in which C + + defines a formal parameter as a reference type