Why do you use typedef when declaring an enum in C++?

typedef enum TokenType
{
    blah1   = 0x00000000,
    blah2   = 0X01000000,
    blah3   = 0X02000000
} TokenType;

enum TokenType { blah1 = 0x00000000, blah2=0x01000000, blah3=0x02000000 };

TokenType my_type;

enum TokenType my_type;

enum TokenType
{
    blah1   = 0x00000000,
    blah2   = 0X01000000,
    blah3   = 0X02000000
};

enum TokenType foo;

typedef enum e_TokenType
{
    blah1   = 0x00000000,
    blah2   = 0X01000000,
    blah3   = 0X02000000
} TokenType;

TokenType foo;

typedef enum MyEnum {
  //...
} MyEnum;

void f( MyEnum x )

void f( enum MyEnum x )

// C++
enum MyEnum {
   // ...
};
void f( MyEnum x ); // Correct C++, Error in C