c++ - 如何找到数组的长度？(How do I find the length of an array?)

Question

Is there a way to find how many values an array has?

(有没有办法找到一个数组有多少个值？)

Detecting whether or not I've reached the end of an array would also work.

(检测我是否已经到达数组末尾也可以。)

  ask by Maxpm translate from so

Answer 1

If you mean a C-style array, then you can do something like:

(如果您的意思是C样式的数组，则可以执行以下操作：)

int a[7];
std::cout << "Length of array = " << (sizeof(a)/sizeof(*a)) << std::endl;

This doesn't work on pointers (ie it won't work for either of the following):

(这不工作的指针（即，它会为以下任一不工作）：)

int *p = new int[7];
std::cout << "Length of array = " << (sizeof(p)/sizeof(*p)) << std::endl;

or:

(要么：)

void func(int *p)
{
    std::cout << "Length of array = " << (sizeof(p)/sizeof(*p)) << std::endl;
}

int a[7];
func(a);

In C++, if you want this kind of behavior, then you should be using a container class;

(在C ++中，如果您想要这种行为，则应该使用容器类。)

probably std::vector .

(可能是std::vector 。)