In this post, I will discuss when to use References and when to use Pointers in C++.<\/p>\n
As usual, I present the conclusion first. I come across this question when learning the compiler course. Pointers make things complicated when designing compilers in C. And in C++ it becomes more complex after references are introduced.<\/p>\n Direct reason that references were introduced in C++ is to support operator overloading.<\/p>\n No<\/strong>. Although some compilers will not report it. It\u2019s still illegal. “The C++ language, as defined by the C++ standard, says it\u2019s illegal.”<\/p>\n No way<\/strong>. Once a reference is bound to an referent, it can not be \u201creseated\u201d to another referent. The reference isn\u2019t a separate object and the reference is its referent<\/strong>. In that sense, a reference is similar to a const pointer such as int* const p (as opposed to a pointer to const such as const int* p).<\/p>\n See the following example to fully understand it.<\/p>\n
\n1. If the varible can be nullptr<\/code>, declare the varible as a pointer;
\n2. If the you want to re-assign the varible, declare the varible as a pointer;
\n3. Otherwise, use references.<\/p>\nDetails<\/h2>\n
Why C++ use pointers?<\/h3>\n
\n
Why introduce references?<\/h3>\n
void f1(const complex* x, const complex* y) \/\/ without references {\n complex z = *x+*y; \/\/ ugly\n \/\/ ...\n}\nvoid f2(const complex& x, const complex& y) \/\/ with references {\n complex z = x+y; \/\/ better\n \/\/ ...\n} \n<\/code><\/pre>\nCan referent be a
nullptr<\/code>?<\/h3>\nFoo &foo_ref = *foo_pointer;\ncout << foo_ref.bar << endl; \/\/ Process finished with exit code 11\n<\/code><\/pre>\nHow to reset a reference variable to another referent?<\/h3>\n
class Foo {\npublic:\n int bar;\n explicit Foo(int x){\n bar = x;\n };\n};\nint main() {\n Foo foo1(1);\n Foo foo2(2);\n Foo &foo_ref = foo1;\n cout << foo1.bar << endl; \/\/1\n cout << foo2.bar << endl; \/\/2\n cout << foo_ref.bar << endl; \/\/1\n foo_ref = foo2; \/\/Actually foo1 is a new copy of foo2 now\n cout << foo1.bar << endl; \/\/2\n cout << foo2.bar << endl; \/\/2\n cout << foo_ref.bar << endl; \/\/2\n}\n\n<\/code><\/pre>\nReference<\/h2>\n