将数组传递给C ++中的函数(Passing Arrays to Function in C++)

将数组传递给C ++中的函数(Passing Arrays to Function in C++) #include <iostream> using namespace std; void printarray (int arg[], int length) { for (int n = 0; n < length; n++) { cout << arg[n] << " "; cout << "\n"; } } int main () { int firstarray[] = {5, 10, 15}; int secondarray[] = {2, 4, 6, 8, 10}; printarray(firstarray, 3); printarray(secondarray, 5); return 0; }

这段代码可以工作，但是我想了解数组是如何传递的。

当从main函数调用printarray函数时，数组的名称将被传递。 数组的名称指的是数组的第一个元素的地址。 这等于int arg[]吗？

#include <iostream> using namespace std; void printarray (int arg[], int length) { for (int n = 0; n < length; n++) { cout << arg[n] << " "; cout << "\n"; } } int main () { int firstarray[] = {5, 10, 15}; int secondarray[] = {2, 4, 6, 8, 10}; printarray(firstarray, 3); printarray(secondarray, 5); return 0; }

This code works, but I want to understand how is the array being passed.

When a call is made to the printarray function from the main function, the name of the array is being passed. The name of the array refers to the address of the first element of the array. How does this equate to int arg[]?

最满意答案

语法

int[]

和

int[X] // Where X is a compile-time positive integer

完全一样

int*

当在函数参数列表中（我省略了可选名称）。

另外，一个数组名称在传递给一个函数（并没有被引用传递时）衰减到指向第一个元素的指针，所以int firstarray[3]和int secondarray[5]衰减为int* s。

当使用相同的索引时，数组解引用和下标语法的指针取消引用（下标语法为x[y] ）也会产生相同元素的左值。

这三个规则相结合，使代码合法化，并且可以预期如何运作; 它只是将指针传递给函数，以及数组的长度，这些数组在数组衰减到指针之后就不可能知道。

The syntaxes

int[]

and

int[X] // Where X is a compile-time positive integer

Are exactly the same as

int*

When in a function parameter list (I left out the optional names).

Additionally, an array name decays to a pointer to the first element when passed to a function (and not passed by reference) so both int firstarray[3] and int secondarray[5] decay to int*s.

It also happens that both an array dereference and a pointer dereference with subscript syntax (subscript syntax is x[y]) yield an lvalue to the same element when you use the same index.

These three rules combine to make the code legal and work how you expect; it just passes pointers to the function, along with the length of the arrays which you cannot know after the arrays decay to pointers.