What does “Class* &cls” mean in C++'s function definition?

Question

I know Class *cls is a pointer, and Class &cls takes the address, but what is

void fucction1( Class *&cls)

If I have Class c

Answer 1

Besides, what James explained in his response, let me add one more important point to it.

While you can write Class* & (reference to pointer) which is perfectly valid in C++ only, you cannot write Class& * (pointer to reference), as you cannot have a pointer to a reference to any type. In C++, pointer to reference is illegal.

§8.3.2/4 from the language specification reads,

There shall be no references to references, no arrays of references, and no pointers to references.

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If I have Class c, what should I pass to function1()?

You can write your calling code like this:

Class *ptrClass;

//your code; may be you want to initialize ptrClass;

function1(ptrClass);

//if you change the value of the pointer (i.e ptrClass) in function1(),
//that value will be reflected here!
//your code