指针参数和数组参数之间有区别吗? [英] Is there a difference between a pointer parameter and an array parameter?

问题描述

void method(double *v)

void method(double v[5])

这两者之间有什么区别吗?

Is there any difference between these two?

第二个是否更具体，例如v限于长度为5个元素?

Is the second one more specific, as in v being constrained to 5 elements in length?

推荐答案

当数组声明为参数类型时，会衰减为指针类型.在您的示例中，

Arrays when declared as parameter types, decay to the pointer types. In your example,

void method(double v[5]);

这里5根本不起作用，无关紧要，您可能会完全忽略，而是这样写:

Here 5 doesn't play any role at all, it is so insignificant that you may omit it altogether, and write this instead:

void method(double v[]);

与上一个声明完全相同.由于它会衰减为指针，因此以上两个与以下内容完全相同:

which is exactly same as the previous declaration. Since it decays into pointer, so the above two are exactly same as:

void method(double *v); //because array decays to pointer, anyway

也就是说，以下所有都是相同功能的声明:

That is, all the following are declarations of the same function:

void method(double v[5]); //ok : declaration 
void method(double v[]);  //ok : redeclaration of the above
void method(double *v);   //ok : redeclaration of the above

全部完全相同.完全没有区别.

ALL are exactly same. No difference at all.

请注意，以下内容不同:

Note that the following is different however:

void f(double (&v)[5]); 

它声明了一个函数，该函数可以采用大小为恰好 5的双精度数组.如果您传递任何其他大小的数组(或传递指针)，则会出现编译错误！

It declares a function which can take array of doubles of size exactly 5. If you pass array of any other size (or if you pass pointers), it will give compilation error!

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