指针与参考 [英] Pointer vs Reference
问题描述
我们可以确认以下内容吗？也有人说，Java也有
引用就像在C ++中，这是一个隐式指针：
指针和参考
-------------- -------
我开始看到什么指针和引用是什么以及它们如何与
相关
到彼此。
$ C $ b在C时代，指针*是*参考。这就是为什么当我们有
int a = 10;
int * pi =& a;
，你可以取消引用它：
* pi = 20;
直到C ++出现，我们才有一个新的参考：
int a = 10;
int i =&一个; //或int i =& a;我不确定语法。
i = 20; //现在我和我都是20
所以这种类型的引用是一个隐式指针......它指向a，
但是
你不能在C中使用这种方式（int * pi =& a）当你使用（i = 20）时，
它会默默地进行解除引用。 （* pi = 20;）
所以引用是新的：指针但是看起来不像指针。
来了考虑一下，在Java和Ruby中，它们也是如此。
a = Car.new
a看起来不像一个指针，但它实际上是一个指针。
我们不要取消引用它来获得像（* a）.value = 10
$ b $这样的属性b或a-> value = 10但是只使用a.value = 10
所以从这一点开始，引用和指针不一样...... a br />
引用是一个指针，它看起来不像指针。
它们都指向某个东西。但是使用的语法（或语法）
看起来不像是C时代的指针。引用是
自动解除引用指针，我们要说什么？或隐含的
指针，或无声指针。指针。
PHP5中的
，
$ a = 10;
$ b =&美元; ＃now $ b含蓄地指向$ a
$ b = 20; ＃now $ b隐含地指向$ a，这是20
$ a = new Foo（hello）; ＃$ a隐式指向Foo对象
#Foo对象是100字节，
＃但$ a只有4个字节
$ b =&美元; ＃$ b隐式指向$ a。
＃$ b是指向指针的指针
＃$ b指向一个四字节指针，即$ a
$ b =新Foo（ok）; #dereference $ b并将其内容设置为
＃指向另一个对象的新指针Foo（ok）
＃即$ a指向Foo（& ; ok"）现在
＃$ b仍然指向$ a，这指向
Foo（ok）
现在，当你打印$ b和$ a时，它们都是Foo（ok）
在我们现在使用的语言中，哪种语言有引用
在思考C ++，Java，（Perl？），Python，PHP5，Ruby都有参考。
在我们现在使用的语言中，哪种语言有参考"一个
"" ;?
我认为C ++，Java，PHP5确实...不确定Python和Ruby。
a = 10;
b =&
一个; ＃now
Can we confirm the following? also someone said, Java also has
"reference" like in C++, which is an "implicit pointer":
Pointer and Reference
---------------------
I am starting to see what pointer and reference are and how they
relate
to each other.
in the C era, a pointer *is* a reference. that''s why when we have
int a = 10;
int *pi = &a;
and you can "dereference it":
*pi = 20;
Until when C++ comes along, then we have a new "reference":
int a = 10;
int i =& a; // or int i = &a; i am not sure about the syntax.
i = 20; // now both a and i are 20
so this type of reference is an implicit pointer... it points to a,
but
you don''t use the way in C (int *pi = &a) And when you use (i = 20),
it does the dereference silently. (*pi = 20;)
so a reference is new: a pointer but "looks like not a pointer".
come to think about it, in Java and Ruby, they are like that too.
a = Car.new
a doesn''t look like a pointer, but it is actually a pointer.
we don''t dereference it to get to the attributes like (*a).value = 10
or a->value = 10 but just use a.value = 10
So from this point on, a reference and a pointer are not the same... a
reference is a pointer "that doesn''t look like a pointer."
they both points to something. but the syntax (or grammar) of usage
doesn''t look like it is a pointer in the C era. a reference is an
"automatically dereferenced" pointer, shall we say? or an "implicit"
pointer, or "silent" pointer.
in PHP5,
$a = 10;
$b =& $a; # now $b implicitly points to $a
$b = 20; # now $b implicitly points to $a, which is 20
$a = new Foo("hello"); # $a implicitly points to a Foo object
# the Foo object is 100 bytes,
# but $a is just 4 bytes
$b =& $a; # $b implicitly points to $a.
# $b is a pointer to pointer
# $b points to a four byte pointer, which is $a
$b = new Foo("ok"); # dereference $b and sets its content to
# a new pointer to another object Foo("ok")
# that is, $a points to Foo("ok") now
# $b still points to $a, which points to
Foo("ok")
So now, when you print $b and $a, they are both Foo("ok")
In language we use nowadays, which language has "reference"
In think C++, Java, (Perl?), Python, PHP5, Ruby all have reference.
In language we use nowadays, which language has "reference" to a
"reference"?
I think C++, Java, PHP5 do... not sure about Python and Ruby.
a = 10;
b =&
a; # now
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