What is the difference between * & and ->

[JoeCamo]

I haven't programmed in about 6 years and I started in a class where I picked up where we left off 6 years ago, needless to say I'm rusty, and didn't really do that well in the first place. I understand that * (e.g. int *value) is designating a pointer to value, and & (e.g. int &value) would give me the address in memory for that value, and -> designates the value to point to something else. But I am not sure when to implement each of these things for different functions when I am passing values and why. If someone could help me understand these concepts I would appreciate it very much so.

(These are just example functions, they aren't part of anything, I just don't see a difference between them except funcTwo would maybe set the address to 5?)

int funcOne ( int *value )
{
     number = 5;
     value = number;
     return value;
}

int funcTwo ( int &value )
{
     number = 5;
     value = number;
     return value;
}

int funcThree ( int value )
{
     int number = 5;
     number = number->value;  //why not just have int *number; then set number = value;
     return number;
}

[vlad from moscow]

There is only one function is syntactically correct if to assume that variable number is a global variable. it is funcTwo. The other two functions are invalid.:)

[JoeCamo]

Well I guess I don't understand is as well as I thought I did in the first place, how could I make the first and third one syntactically correct?

[keskiverto]

-> is used in referring to a member of an object via pointer.

struct Foo {
  void bar ():
};

int main() {
  Foo foo;
  Foo * gaz = &foo; // store address of object foo in pointer gaz
  Foo & qux = foo; // create a reference to object foo
  foo.bar(); // call member function of object
  gaz->bar(); // call same function of same object via the pointer
  qux.bar(); // call same function of same object via the reference
  return 0;
}

Your funcTwo takes a reference parameter. Reference is not same as address-of although both use the same symbol &.

Edit:
A pointer is a special type of variable that stores a memory address and has a dereferencing operator that allows accessing the value stored in the memory address.

void funcOne( int * value ) {
  *value = 42; // write 42 to whereever the value points to
}

int main() {
  int foo = 0;
  // assert( 0 == foo );
  funcOne( &foo );
  // during the call of funcOne value holds the address of foo of main()
  // funcOne will assign 42 into that memory location
  // assert( 42 == foo );
  return 0;
}

[JoeCamo]

Awesome this helps a lot, thank you very much.

[vlad from moscow]

These functions are primitive and shown only for demonstrative purposes.

int funcOne ( int *value )
{
     int number = 5;
     *value = number;
     return *value;
}

int funcTwo ( int &value )
{
     int number = 5;
     value = number;
     return value;
}

int funcThree ( int value )
{
     struct S { int value; } *number = new S;
     number->value = value;
     // some other stuff with number 
     value = number->value;
     delete number;
 
     return value;
}