关于C/C++中char*之间的比较和数组之间的比较的问题

Question

char a[] = "abc";
char b[] = "abc";
char* c = "abc";
char* d = "abc";

if( a==b )
{
    cout<< "a[] and b[] are equal!" << endl;
}else if( a!=b )
{
      cout<< "a[] and b[] are not equal!" << endl;
}

if( c==d )
{
      cout<< "*c and *d are equal!" << endl;
}else if( c!=d )
{
      cout<< "*c and *d are not equal!" << endl;
}

请问输出结果是什么？为什么是这种结果？